Andrew Kramer has a new After Effects tutorial on Video Copilot, 3D Ball Dispersion:
"In this tutorial we will learn a technique to offset the animation of the CC Ball Action effect to create a cool transition. This effect uses only built-in plug-in and offers creative flexibility for a variety of looks. The project file also includes a script for offsetting the layers by 1 frame to make the process easier. The tutorial is about 25 minutes but the time will fly by!"
The built-in CC Ball Action filter "transforms the source layer into an array of balls. You can rotate and twist the array around a specified axis and scatter the array in all directions." Ball Action is a very old filter that hasn't been upgraded beyond support for the AE comp camera, but using the Brighten Twist control makes things interesting beyond the basics described by the intro by Brian Maffitt from an old Total Training video at Toolfarm.
Other tutorials can be found around the net, including Jumbotrons in After Effects, Harry Frank's Rippling Circles, Sound Reacting 3D Waveform without 3rd Party Plugins from Satya Meka, and Give Your Type Some Ball Action from Adam at AETuts.