AS3 Signals is an awesome open-source project created by Robert Penner that will make you re-think the way you approach events in all of your future projects. I put together this video tutorial (mostly to force myself to learn it) and I've been REALLY impressed with it so far. Go ahead and give it a watch:
For more info on AS3 Signals, check out http://wiki.github.com/robertpenner/as3-signals/ and join the google group.
Download the swc: as3-signals.swc
*note - I just realized that I said, "it's really, really easy and it's also really simple" during the video. That's really just a testament to how easy it is ;)
*second note - thanks for all the votes on video resolution preferences. I'll be sticking with 1024x768 from here on out.