Small world – this project from Columbia University finds that while there are probably less than 6 degrees, the network entertains requests for favours only about a third of the time, and that it’s not as hub-and-spoke as scale-free networks would have us imagine. via NYTimes
A good (but technical) overview of complex networks literature (PDF). If you do pick it up, just glance through “III. Properties of networks”. It gives a good sense of what little we know of real-world networks.
Growth, Form, Function, and Crashes: an article from the Santa Fe institute. It explains scale-free fairly well. The point is, scale-free networks have a few hubs. If you knock a hub out, the network is fragmented. But your chance of knocking a hub out by random is small, since there are so few of them. That makes scale-free networks reliable as well as vulnerable. Slightly more technical details at PhysicsWeb by the creators of scale-free networks. It also says that if you design a network, it may not be scale-free. But if you let it evolve, it probably will be.
The Internet is a scale free network.