http://www.cambrianexplosion.com/
This is one of the coolest things I've seen on the internet recently. Anyone who is familiar with R. Dawkins' "Weasel", Greg Egan's work like "Crystal Nights" etc and the simulation argument might find it fascinating.
Addiction Warning: I've spent 8 hours playing with this in the last 2 days...
Thanks! I had abandoned it, but now I am fired up and am planning to keep working on it.
I intend to put up a FAQ over the weekend that will explain everything. I know right now there's all these settings and some buttons don't work so you can see it was left unfinished.
I'm looking into using Web Workers to speed it up, but another thing you can do in the meantime especially if you plan on leaving it to come back to is set the render to "None". This makes it runs the entire population simultaneously so it goes through the generations at a much faster clip. I've gone up to thousands of generations after leaving it over night.