Swarm Behavior
Robert Hodgin (one of the co-founders of Barbarian Group, where I work) is posting some amazing videos of his swarm experiments with Cinder, a C++ library for doing crazy visual stuff.
His latest experiments in flocking are based off three simple rules (which, as Robert points out, are equally apt for life):
1) If I am far away from my neighbors, move towards them.
2) If I am too close to my neighbors, move away from them.
3) If I am neither too close or too far from my neighbors, move with them.