Click: What Millions of People Are Doing Online and Why it Matters, by Bill Tancer.
Bill Tancer loves data, and in his job he gets to work with a lot of it. He works for Hitwise, a company that analyzes online information, particularly search terms and online traffic. One of the examples that he gives in the book is that searches for prom dresses spikes in early January. He could come up with no explanation for this data, so he spoke with insiders in the prom dress industry, who were equally as clueless - they target their marketing for April and May, since most proms take place in late May. Finally, after sharing his data at a conference, a magazine publisher clued him in to the fact that teen magazines publish prom fashion issues in late December - a fact that, I'm sure, the prom dress industry needs to know.
While this book is in the same category as The Tipping Point or Freakonomics, it's not quite as good. Perhaps Mr. Tancer, being a data guy, is a bit more uncomfortable with "the big picture". But there is still a lot of great information here. I found the discussions of Web 2.0 and social networking particularly interesting.
Joe Hodnicki of the Law Librarian Blog writes a review here.