Jeremy Philips sent me this book last month and downed it in one long plane ride. This is a fantastic book and one definitely worth reading. (and if you want me to send you my copy, free book to the first friend of mine that replies).
Predictably Irrational: The Hidden Forces That Shape Our Decisions by Dan Ariely is a great book by a revealing and insightful economist and social scientist. if you liked freakonomics, you'll love this book. in fact, if you don't love this book, you're probably not very interesting. really. it is that good.
more information available at Ariely's web site:
http://www.predictablyirrational.com