Example - JavaScript animations - canvas based. I am having a "ball" playing around with this task! Obviously a man with way too much time on his hands :).

This stuff is totally contageous - Below are a sequence of links that take you through the dev process. Promise that this is the end of it

bouncing-1.html
rotate-1.html
balls
ball.many.html
ball-angle-bounce.html
ball-multi-angle-bounce.html
ball-throw.html