If many hands make light work, what do many brains make? Author and teacher Clay Shirky, who studies the effects of the Internet on society, argues that we live in a time of "cognitive surplus," a pool of brainpower that can be tapped, through the Internet, by engaging people's free time to think and solve problems together. In books, blogs, and TED Talks, Shirky explains at length why an infinite number of heads is way better than one.