diff --git a/src/as/com/threerings/README.txt b/src/as/com/threerings/README.txt
index 7def758d9..ee4de3e0c 100644
--- a/src/as/com/threerings/README.txt
+++ b/src/as/com/threerings/README.txt
@@ -16,9 +16,10 @@ Design decisions
 
 - We need a realistic HashMap implementation. Using Object properties
   (a-la my SimpleMap) is not going to cut it because keys must always
-  be Strings and there's no way to *really* remove a value from an Object
-  (you can set the property to null, but now the property is forever defined:
-  the key is not cleared)
+  be Strings.<strike>and there's no way to *really* remove a value from
+  an Object (you can set the property to null, but now the property is
+  forever defined: the key is not cleared)</strike>
+  ***Update: the 'delete' operator removes properties.
 
   mx.utils.UIDUtil.getUID() can be used to generate a (huge) unique String
   for any object for use as a key or something.
@@ -81,10 +82,9 @@ Notes
   and accessing only public properties of the main class from the helper.
 
 
-- Similarly, I'm unclear about sandboxes. If a user-created .swf is playing
-  inside ours, I don't know if it can interact with our classes, and if so,
-  what happens if it proceeds to define a class like
-  com.threerings.presents.client.Client?
+- Sandboxing classes is done with ApplicationDomains. When we load a sub-swf
+  we'll want to put it into a different domain so that nothing malicious
+  can be done to our classes.
 
 - <strike>constructors do not defaultly call super()- be sure to do it explicitely.
   Maybe we should get in the habit of doing it in Java for consistency and
@@ -169,6 +169,14 @@ ActionScript
   Perhaps we'll want a util method that always generates an error if the
   object's type is not identical or a subclass of the casted-to type.
 
+  ***Update:
+     var o1 :String = null;
+     var o2 :String = String(o1); // ends up being "" or something
+
+     The 2nd kind of cast destroys null, at least for String. So fuck that,
+     I was trying to use it when pulling a value out of a hash, but if it
+     wasn't there it got booched.
+
 
 - Pitfall! This is perfectly legal:
      var b :int = 3;
@@ -198,5 +206,10 @@ ActionScript
   me from correctly streaming arrays, as we need to know if the class
   is final. I can't just pass an instance in because it may be a pain
   to construct, it may even be unconstructable if the type of the array
-  is an interface. The adobe forums are broken right now, but I'm going
-  to post a request for enhancement so that we can get this information.
+  is an interface. Posted as a request for enhancement on the AS3.0 forums.
+
+
+- Actionscript's property accessors are a cool feature, but beware hidden
+  performance issues: accessing a simple property of a variable
+  (like myArray.length) may actually be executing arbitrary code, possibly
+  creating many objects, each time.
diff --git a/src/as/com/threerings/io/ObjectInputStream.as b/src/as/com/threerings/io/ObjectInputStream.as
index fd9d93bc6..dd4da198e 100644
--- a/src/as/com/threerings/io/ObjectInputStream.as
+++ b/src/as/com/threerings/io/ObjectInputStream.as
@@ -28,14 +28,6 @@ public class ObjectInputStream
         _source = source;
     }
 
-    /**
-     * Add a translation that should be used when writing objects.
-     */
-    public function addTranslation (oldName :String, newName :String) :void
-    {
-        _translations[oldName] = newName;
-    }
-
     public function readObject () :Object
         //throws IOError
     {
@@ -57,13 +49,8 @@ public class ObjectInputStream
                 code *= -1;
 
                 // read in the class metadata
-                var cname :String = readUTF();
+                var cname :String = Translations.getFromServer(readUTF());
                 Log.debug("read cname: " + cname);
-                // if we have a translation, use it
-                var tname :String = _translations[cname];
-                if (tname != null) {
-                    cname = tname;
-                }
                 var streamer :Streamer = Streamer.getStreamerByJavaName(cname);
 
                 cmap = new ClassMapping(code, cname, streamer);
@@ -215,9 +202,5 @@ public class ObjectInputStream
 
     /** A map of short class code to ClassMapping info. */
     protected var _classMap :Array = new Array();
-
-    /** An collection of class name translations to use when unserializing
-     * objects. */
-    protected var _translations :SimpleMap = new SimpleMap();
 }
 }
diff --git a/src/as/com/threerings/io/ObjectOutputStream.as b/src/as/com/threerings/io/ObjectOutputStream.as
index 1d8e3e080..bc5f7bbb6 100644
--- a/src/as/com/threerings/io/ObjectOutputStream.as
+++ b/src/as/com/threerings/io/ObjectOutputStream.as
@@ -15,15 +15,6 @@ public class ObjectOutputStream
         _targ = targ;
     }
 
-    /**
-     * Add a classname translation for rewriting the names of objects
-     * that we send to the server.
-     */
-    public function addTranslation (oldName :String, newName :String) :void
-    {
-        _translations[oldName] = newName;
-    }
-
     public function writeObject (obj :Object) :void
         //throws IOError
     {
@@ -35,7 +26,7 @@ public class ObjectOutputStream
 
         var cname :String = ClassUtil.getClassName(obj);
         // look up the class mapping record
-        var cmap :ClassMapping = _classMap[cname];
+        var cmap :ClassMapping = (_classMap.get(cname) as ClassMapping);
 
         // create a class mapping if we've not got one
         if (cmap == null) {
@@ -48,18 +39,13 @@ public class ObjectOutputStream
             }
 
             cmap = new ClassMapping(_nextCode++, cname, streamer);
-            _classMap[cname] = cmap;
+            _classMap.put(cname, cmap);
 
             // TODO: if _nextCode blows short, log an error
 
-            // see if there's a translation we should use
-            var tname :String = _translations[cname];
-            if (tname != null) {
-                cname = tname;
-            }
-
             writeShort(-cmap.code);
-            writeUTF((streamer == null) ? cname : streamer.getJavaClassName());
+            writeUTF((streamer == null) ? Translations.getToServer(cname)
+                                        : streamer.getJavaClassName());
 
         } else {
             writeShort(cmap.code);
@@ -200,8 +186,5 @@ public class ObjectOutputStream
 
     /** A map of classname to ClassMapping info. */
     protected var _classMap :SimpleMap = new SimpleMap();
-
-    /** A map of classname translations. */
-    protected var _translations :SimpleMap = new SimpleMap();
 }
 }
diff --git a/src/as/com/threerings/io/Streamer.as b/src/as/com/threerings/io/Streamer.as
index 02579c8a2..3e688afc5 100644
--- a/src/as/com/threerings/io/Streamer.as
+++ b/src/as/com/threerings/io/Streamer.as
@@ -48,6 +48,10 @@ public class Streamer
     {
         initStreamers();
 
+        if (jname.charAt(0) === "[") {
+            // Oh ghod
+        }
+
         for each (var streamer :Streamer in _streamers) {
             if (streamer.getJavaClassName() === jname) {
                 return streamer;
@@ -86,7 +90,7 @@ public class Streamer
         if (obj is Array) {
             trace("Arrays not yet done. Crap!");
             /**
-            var arr :Array = (obj as Array); // not strictly necessary
+            var arr :Array = Array(obj); // not strictly necessary
             var length :int = arr.length;
             out.writeInt(length);
             */
diff --git a/src/as/com/threerings/presents/client/ClientDObjectMgr.as b/src/as/com/threerings/presents/client/ClientDObjectMgr.as
index c4c4f8c92..8c3427546 100644
--- a/src/as/com/threerings/presents/client/ClientDObjectMgr.as
+++ b/src/as/com/threerings/presents/client/ClientDObjectMgr.as
@@ -208,14 +208,13 @@ public class ClientDObjectMgr
 
         } else if (obj is UnsubscribeResponse) {
             var oid :int = obj.getOid();
-            if (_dead[oid] == null) {
+            if (_dead.remove(oid) == null) {
                 Log.warning("Received unsub ACK from unknown object " +
                             "[oid=" + oid + "].");
             }
-            _dead[oid] = undefined;
 
         } else if (obj is FailureResponse) {
-            var oid :int = obj.getOid();
+            var oid :int = (obj as FailureResponse).getOid();
             notifyFailure(oid);
 
         } else if (obj is PongResponse) {
@@ -250,9 +249,9 @@ public class ClientDObjectMgr
 
         // look up the object on which we're dispatching this event
         var toid :int = event.getTargetOid();
-        var target :DObject = _ocache[toid];
+        var target :DObject = (_ocache.get(toid) as DEvent);
         if (target == null) {
-            if (_dead[toid] === undefined) {
+            if (_dead.get(toid) == null) {
                 Log.warning("Unable to dispatch event on non-proxied " +
                     "object [event=" + event + "].");
             }
@@ -269,7 +268,7 @@ public class ClientDObjectMgr
 //                 Log.info("Pitching destroyed object " +
 //                          "[oid=" + toid + ", class=" +
 //                          StringUtil.shortClassName(target) + "].");
-                _ocache[toid] = undefined;
+                _ocache.remove(toid);
             }
 
             // have the object pass this event on to its listeners
@@ -295,7 +294,7 @@ public class ClientDObjectMgr
 
         var oid :int = obj.getOid();
         // stick the object into the proxy object table
-        _ocache[oid] = obj;
+        _ocache.put(oid, obj);
 
         // let the penders know that the object is available
         var req :PendingRequest = (_penders.remove(oid) as PendingRequest);
@@ -321,8 +320,7 @@ public class ClientDObjectMgr
     protected function notifyFailure (oid :int) :void
     {
         // let the penders know that the object is not available
-        var req :PendingRequest = _penders[oid];
-        _penders[oid] = undefined;
+        var req :PendingRequest = (_penders.remove(oid) as PendingRequest);
         if (req == null) {
             Log.warning("Failed to get object, but no one cares?! " +
                         "[oid=" + oid + "].");
@@ -345,10 +343,10 @@ public class ClientDObjectMgr
         // Log.info("doSubscribe: " + oid + ": " + target);
 
         // first see if we've already got the object in our table
-        var obj :DObject = _ocache[oid];
+        var obj :DObject = (_ocache.get(oid) as DObject);
         if (obj != null) {
             // clear the object out of the flush table if it's in there
-            _flushes[oid] = undefined;
+            _flushes.remove(oid);
             // add the subscriber and call them back straight away
             obj.addSubscriber(target);
             target.objectAvailable(obj);
@@ -356,7 +354,7 @@ public class ClientDObjectMgr
         }
 
         // see if we've already got an outstanding request for this object
-        var req :PendingRequest = _penders[oid];
+        var req :PendingRequest = (_penders.get(oid) as PendingRequest);
         if (req != null) {
             // add this subscriber to the list of subscribers to be
             // notified when the request is satisfied
@@ -367,7 +365,7 @@ public class ClientDObjectMgr
         // otherwise we need to create a new request
         req = new PendingRequest(oid);
         req.addTarget(target);
-        _penders[oid] = req;
+        _penders.put(oid, req);
         // Log.info("Registering pending request [oid=" + oid + "].");
 
         // and issue a request to get things rolling
@@ -380,7 +378,7 @@ public class ClientDObjectMgr
      */
     protected function doUnsubscribe (oid :int, target :Subscriber) :void
     {
-        var dobj :DObject = _ocache[oid];
+        var dobj :DObject = (_ocache.get(oid) as DObject);
         if (dobj != null) {
             dobj.removeSubscriber(target);
 
@@ -401,8 +399,8 @@ public class ClientDObjectMgr
         // have it around anymore; once our unsubscribe message is
         // processed, it'll be 86ed
         var ooid :int = obj.getOid();
-        _ocache[ooid] = undefined;
-        _dead[ooid] = obj;
+        _ocache.remove(ooid);
+        _dead.put(ooid, obj);
 
         // ship off an unsubscribe message to the server; we'll remove the
         // object from our table when we get the unsub ack
@@ -416,10 +414,10 @@ public class ClientDObjectMgr
     protected function flushObjects () :void
     {
         var now :Number = new Date().getTime();
-        for (var oid :String in _flushes) {
-            var rec :FlushRecord = _flushes[oid];
+        for (var oid :String in _flushes.keys()) {
+            var rec :FlushRecord = (_flushes.get(oid) as FlushRecord);
             if (rec.expire <= now) {
-                _flushes[oid] = undefined;
+                _flushes.remove(oid);
                 flushObject(rec.obj);
             }
         }
diff --git a/src/as/com/threerings/presents/client/Communicator.as b/src/as/com/threerings/presents/client/Communicator.as
index 8eebf1dd8..c36194716 100644
--- a/src/as/com/threerings/presents/client/Communicator.as
+++ b/src/as/com/threerings/presents/client/Communicator.as
@@ -14,6 +14,7 @@ import com.threerings.io.FrameAvailableEvent;
 import com.threerings.io.FrameReader;
 import com.threerings.io.ObjectInputStream;
 import com.threerings.io.ObjectOutputStream;
+import com.threerings.io.Translations;
 
 import com.threerings.presents.Log;
 
@@ -57,9 +58,8 @@ public class Communicator
 
     private function addClassTranslations () :void
     {
-        _inStream.addTranslation("com.threerings.presents.dobj.DSet$Entry",
-            "com.threerings.presents.dobj.DSetEntry");
-        _outStream.addTranslation("com.threerings.presents.dobj.DSetEntry",
+        Translations.addTranslation(
+            "com.threerings.presents.dobj.DSetEntry",
             "com.threerings.presents.dobj.DSet$Entry");
     }
 
@@ -102,7 +102,7 @@ public class Communicator
         // write the message (ends up in _outBuffer)
         _outStream.writeObject(msg);
 
-        //Log.debug("outBuffer: " + Util.bytesToString(_outBuffer));
+        Log.debug("outBuffer: " + Util.bytesToString(_outBuffer));
 
         // Frame it by writing the length, then the bytes.
         // We add 4 to the length, because the length is of the entire frame
diff --git a/src/as/com/threerings/presents/client/InvocationDirector.as b/src/as/com/threerings/presents/client/InvocationDirector.as
index 9623c3fd6..6b8f95b4a 100644
--- a/src/as/com/threerings/presents/client/InvocationDirector.as
+++ b/src/as/com/threerings/presents/client/InvocationDirector.as
@@ -103,7 +103,7 @@ public class InvocationDirector
         var reg :InvocationRegistration = new InvocationRegistration(
             decoder.getReceiverCode(), nextReceiverId());
         _clobj.addToReceivers(reg);
-        _receivers[reg.receiverId] = decoder;
+        _receivers.put(reg.receiverId, decoder);
     }
 
     /**
@@ -139,7 +139,7 @@ public class InvocationDirector
 
                 // create a mapping for this marshaller so that we can
                 // properly dispatch responses sent to it
-                _listeners[lm.requestId] = lm;
+                _listeners.put(lm.requestId, lm);
             }
         }
 
@@ -187,7 +187,7 @@ public class InvocationDirector
             (reqId :int, methodId :int, args :Array) :void
     {
         var listener :ListenerMarshaller = 
-            (_listeners.remove(reqId) as ListenerMarshaller); 
+            (_listeners.remove(reqId) as ListenerMarshaller);
         if (listener == null) {
             Log.warning("Received invocation response for which we have " +
                         "no registered listener [reqId=" + reqId +
@@ -229,7 +229,7 @@ public class InvocationDirector
     {
         // look up the decoder registered for this receiver
         var decoder :InvocationDecoder =
-            (_receivers[receiverId] as InvocationDecoder);
+            (_receivers.get(receiverId) as InvocationDecoder);
         if (decoder == null) {
             Log.warning("Received notification for which we have no " +
                         "registered receiver [recvId=" + receiverId +
@@ -268,11 +268,11 @@ public class InvocationDirector
     protected function flushListeners (now :Number) :void
     {
         var then :Number = now - LISTENER_MAX_AGE;
-        for (var skey :String in _listeners) {
+        for (var skey :String in _listeners.keys()) {
             var lm :ListenerMarshaller =
-                (_listeners[skey] as ListenerMarshaller);
+                (_listeners.get(skey) as ListenerMarshaller);
             if (lm.mapStamp < then) {
-                _listeners.clear(skey);
+                _listeners.remove(skey);
             }
         }
     }
diff --git a/src/as/com/threerings/presents/client/TestClient.as b/src/as/com/threerings/presents/client/TestClient.as
index c7d79c603..f17e094c6 100644
--- a/src/as/com/threerings/presents/client/TestClient.as
+++ b/src/as/com/threerings/presents/client/TestClient.as
@@ -15,13 +15,41 @@ public class TestClient extends Client
         setServer("tasman.sea.earth.threerings.net", DEFAULT_SERVER_PORT);
         logon();
 
-        var a :Object = new HelperClass(this);
+        var g1 :String = null;
+        var g2 :String = String(g1);
+        Log.debug("foo: " + (g1 === g2));
 
-        Log.debug("instance: " + describeType(a).toXMLString());
-        Log.debug("class   : " + describeType(HelperClass).toXMLString());
+        var duckie :Duck = new Goose();
+        duckie.screw();
+
+        var arr :Array = new Array();
+        arr[0] = "Florp";
+        arr[1] = "Blanger";
+        arr[2] = "Swissbrat";
+
+        for (var key:* in arr) {
+            Log.debug("a key=" + key + " -> " +  arr[key]);
+        }
+        delete arr[1];
+        arr["1"] = "oinkenheimer";
+        for (var key:* in arr) {
+            Log.debug("a key=" + key + " -> " +  arr[key]);
+        }
+        Log.debug("length: " + arr.length);
+        Log.debug("arr[0]: " + arr[0]);
+        Log.debug("arr[1]: " + arr[1]);
+        Log.debug("arr[2]: " + arr[2]);
 
         /*
-        var b :Object = new PooperClass();
+        var a :Object = new OldClass();
+        var c :Class = OldClass;
+
+        Log.debug("instance: " + describeType(a).toXMLString());
+        Log.debug("class   : " + describeType(Pork).toXMLString());
+        */
+
+        /*
+        var b :Object = new OldClass();
         var c :Object = 2.4;
         var d :Object = new HooperClass(this);
 
@@ -74,6 +102,13 @@ public class TestClient extends Client
 import com.threerings.presents.Log;
 import com.threerings.presents.client.TestClient;
 
+dynamic class OldClass
+{
+    public function OldClass ()
+    {
+    }
+}
+
 class HelperClass
 {
     public function HelperClass (cli :TestClient)
@@ -113,10 +148,3 @@ final class HooperClass extends HelperClass
         // nada
     }
 }
-
-class PooperClass
-{
-    public function PooperClass ()
-    {
-    }
-}
diff --git a/src/as/com/threerings/presents/dobj/EntryRemovedEvent.as b/src/as/com/threerings/presents/dobj/EntryRemovedEvent.as
index 765f711c7..27cf95831 100644
--- a/src/as/com/threerings/presents/dobj/EntryRemovedEvent.as
+++ b/src/as/com/threerings/presents/dobj/EntryRemovedEvent.as
@@ -5,7 +5,6 @@ import flash.util.StringBuilder;
 import com.threerings.io.ObjectInputStream;
 import com.threerings.io.ObjectOutputStream;
 
-import com.threerings.util.Comparable;
 
 import com.threerings.presents.Log;
 
@@ -31,7 +30,7 @@ public class EntryRemovedEvent extends NamedEvent
      * @param oldEntry the previous value of the entry.
      */
     public function EntryRemovedEvent (
-            targetOid :int, name :String, key :Comparable, oldEntry :DSetEntry)
+            targetOid :int, name :String, key :Object, oldEntry :DSetEntry)
     {
         super(targetOid, name);
         _key = key;
@@ -41,7 +40,7 @@ public class EntryRemovedEvent extends NamedEvent
     /**
      * Returns the key that identifies the entry that has been removed.
      */
-    public function getKey () :Comparable
+    public function getKey () :Object
     {
         return _key;
     }
@@ -99,10 +98,10 @@ public class EntryRemovedEvent extends NamedEvent
     public override function readObject (ins :ObjectInputStream) :void
     {
         super.readObject(ins);
-        _key = (ins.readObject() as Comparable);
+        _key = ins.readObject();
     }
 
-    protected var _key :Comparable;
+    protected var _key :Object;
     protected var _oldEntry :DSetEntry = UNSET_OLD_ENTRY;
 }
 }
diff --git a/src/as/com/threerings/util/ClassUtil.as b/src/as/com/threerings/util/ClassUtil.as
index 64d059f0e..f727ba695 100644
--- a/src/as/com/threerings/util/ClassUtil.as
+++ b/src/as/com/threerings/util/ClassUtil.as
@@ -26,6 +26,7 @@ public class ClassUtil
 
     public static function getClassByName (cname :String) :Class
     {
+        // see also ApplicationDomain.currentDomain.getClass(cname)
         return flash.util.getClassByName(cname);
     }
 
diff --git a/src/as/com/threerings/util/SimpleMap.as b/src/as/com/threerings/util/SimpleMap.as
index 60fa7a55e..407328d50 100644
--- a/src/as/com/threerings/util/SimpleMap.as
+++ b/src/as/com/threerings/util/SimpleMap.as
@@ -4,15 +4,44 @@ package com.threerings.util {
  * Marker class that allows us to use ActionScript's built-in hashing
  * function without hassle.
  */
-public dynamic class SimpleMap extends Object
+public class SimpleMap extends Object
 {
+    public function clear () :void
+    {
+        _data = new Object();
+    }
+
+    public function get (key :Object) :Object
+    {
+        var skey :String = key.toString();
+        return _data[skey];
+    }
+
+    public function keys () :Array
+    {
+        var arr :Array = new Array();
+        for (var skey :String in _data) {
+            arr.push(skey);
+        }
+        return arr;
+    }
+
+    public function put (key :Object, value :Object) :Object
+    {
+        var skey :String = key.toString();
+        var oldValue :Object = _data[skey];
+        _data[skey] = value;
+        return oldValue;
+    }
+
     public function remove (key :Object) :Object
     {
-        // I'm not sure this really works
         var skey :String = key.toString();
-        var value :Object = this[skey];
-        this[skey] = undefined;
+        var value :Object = _data[skey];
+        delete _data[skey];
         return value;
     }
+
+    private var _data :Object = new Object();
 }
 }
diff --git a/src/as/com/threerings/util/TypedArray.as b/src/as/com/threerings/util/TypedArray.as
index 91613ec9b..ab39ea13c 100644
--- a/src/as/com/threerings/util/TypedArray.as
+++ b/src/as/com/threerings/util/TypedArray.as
@@ -1,7 +1,5 @@
 package com.threerings.util {
 
-import flash.util.describeType;
-
 import mx.utils.ObjectUtil;
 
 import com.threerings.io.ArrayMask;
@@ -83,6 +81,7 @@ public dynamic class TypedArray extends Array
      * except gives it a clue as to how to stream to our server. */
     protected var _type :Class;
 
+    /** Whether or not the type of the array represents a final class. */
     protected var _final :Boolean;
 
     protected var _delegate :Streamer;