Here's a nifty video by Charles Leadbeater, author of We Think: The Power of Mass Creativity. The book looks interesting. I don't know how much it overlaps Clay Shirky's phenomenally excellent book, Here Comes Everybody, but I might have to get it (it's only available at Amazon UK?).
Many thanks to Rob Jacobs for leading me to this video. I have a feeling I'll be using it in some presentations in the near future.