"Linked: How Everything Is Connected to Everything Else and What It Means," Albert-Laszlo Barabasi

I thoroughly enjoyed this book. I have been fascinated by emergent systems since I saw a demo of swarming behavior back in the day. This book does a great job of showing how a small number of simple rules can create a network that mimics the organization of everything from the Internet to the web of chemical reactions in the cell. It also explains why Kevin Bacon isn't all that connected relatively speaking and we should be playing four degrees of Donald Pleasence.