This little java applet called the "SodaPlay Constructor" (found at http://www.sodaplay.com/constructor/index.htm) is absolutely amazing. It is basically all about physics and movement, with a bit of 3d look to it. Sometimes when I'm bored (ie. during study hall) I go and mess around with it for a while, trying to see what I can create.

Well, check it out when you have time. You'd probably like it.

-Chris