This looks super neat, I can't wait to see how it develops! I love these sorts of simulations, I was really inspired by http://www.darwinpond.com/ when I was back at college, and I have dabbled in a few sims myself, I'm working on something similar to The Bibites actually =] http://troydev.proggle.net/projects-trilobytes.php though it doesn't look nearly as polished yet