VideoCopilot notes a new method by Maltaannon (Poland's Jerzy Drozda) to extrude any vector based layer to give it real 3D looks and control (along with Shape Layer modifiers) inside After Effects.
In addition to a video explanation, he provides CE ShapeExtruder, one of his CustomEffects (installation instructions here), and a project and FFX. His custom effects (there are others) combine presets with expressions to look and behave like standard plug-ins, and requires a DLL install. Jerzy's stuff is also on Creative Cow.
Update: I'm just bumping this back to the top from 9/30/07 since it's cool.
Update 2: Maltaannon now has a YouTube channel, so here's his videos: