Here's a great primer (and a fun game) on using the HTML5 canvas for sprite based games:

http://googlecode.blogspot.com/2011/...ipt-html5.html

It talks about optimizing draw calls for quick smooth animation. Once you're done reading, get yourself a modern browser (FF/Chrome/Safari) and try it out below!
http://playbiolab.com/

More info on the tool used, ImpactJS, to create the game (by the developer):
http://impactjs.com/documentation/vi...-create-a-game