Freakonomics by Steven Levitt and Stephen Dubner
Kind of a mixed bag, but worth reading. The theories are well thought out and thoroughly interesting. The structure of the chapters, however, leaves something to be desired. They start out building a central theme (around how people respond to incentives), but it's largely abandoned halfway through. And the transitions between passages (or lack thereof) within each chapter somewhat weaken the main ideas; as though the authors are just rattling off examples and not really making connections. Levitt's claim of being a "rogue economist" doesn't go unfounded, but it seems like he thought a "rogue" didn't have to write that well.