This is a basic implementation of Conway's Game of Life. I use this on occasion to stress test browsers. When I wrote this in 2008 only Chrome managed to get more than a frame per second, and that was with a 30 x 30 table. The table is now 75 x 75 because it hits the limit set on recursive function calls in some browsers (cowards).
If you'd like to see if your broweser can do better, update the value in onload="startlife(75)", if the table isn't rendered then the JavaScript has crashed out.
Use this link to preview life.html in all its CPU consuming glory.