Owen Densmore's Backspaces.net
Owen Densmore is a former Apple fellow (his is one of the signatures molded into the plastic on the inside of the early Mac models) and Chief Scientist at Sun Microsystems. For the last decade or so, he's been working as a consultant, primarily in areas related to agent-based modeling and simulation. His website has NetLogo tutorials and examples, as well as a wide variety of other content on programming, simulation, complexity, etc.