<p>Is it possible to programmatically force a full garbage collection run in ActionScript 3.0?</p>

<p>Let's say I've created a bunch of Display objects with eventListeners and some of the DO's have been removed, some of the eventListeners have been triggered and removed etc... Is there a way to force garbage collection to run and collect everything that is available to be collected?</p>

Yes, it's possible, but it is generally a bad idea. The GC should have a better idea of when is a good time to run than you should, and except for a very specific case, like you just used 500MB of memory and you need to get it back ASAP, you shouldn't call the GC yourself.
In Flash 10, there is a
```
System.gc()
```
method you can call (but please don't, see above) - keep in mind System.gc() only works in the debugging version of Flash player 10+.
In Flash 9, there is an unsupported way to force it via an odd LocalConnection command, but it may not work in all versions. See
this post
by Grant Skinner.