Complexification

Complexification’s Gallery is an awesome, hypnotic site. This is Jared Tarbell’s art created by algorithms, and it can be drawn in real-time in front of you. As an unusual bonus, you can see the applet source code for the non-Flash ones. The software tool used to create the applets is
Processing, an open-source visual and audio art programming language (which I will download after I finish playing with Tarbell’s animations).

Update to add: There's some entertaining explanation of the simulations behind the art, especially the robot offspring one: Offspring is a visualization of the pair bonding process of a theoretical robot colony. Each robot is assembled, ages through youth, comes into a reproductive stage, and eventually dies of fatigue. If a robot is lucky enough to find a mate during it's reproductive stage, baby robots may be assembled.