Sodaconstructor has been around the Internet for a long time, but it's nice to see it again. What is it?
It's a java-based kinetic model that you can play with by changing parameters like the strength of gravity, friction, spring stiffness, and muscle "wave" (you'll see).
You can even build your own! http://www.sodaplay.com/constructor/player.htm - Thanks Estefania!