Something I meant to post ages ago, this is something I came across for the first time in the Interactive Storytelling book by Glassner. Its an excellent example of life-like behaviour being exhibited by simple systems, describing a setup of a car fitted with light sensors and motors and how they can demonstrate definable characteristics with almost no complexity. Definitely want to build a little simulator for this sometime.
Its made be want to get Programming Game AI by Example, which is meant to be a fantastic book on the subject.