Freakonomics: A Rogue Economist Explores the Hidden Side of Everything by Steven D. Levitt, Stephen J. Dubner
this was an amazing book. buy it, read it, then buy it for a friend. (and it is also available on Audible -- so I downloaded it and listened) ...
you've probably heard of the book by now ... it is Levitt's take on crime, child birth, real estate agents, and more. the book is remarkably interesting.
it was recommended to me by Andrew McLaughlin and Tom Spengler. I even found out this weekend that Jon Hoffman read it.