Levitt, Steven D. and Dubner, Stephen J. Freakonomics. New York: HarperCollins Publishers Inc., 2005. ISBN: 006073132X
This is a well-deserved best seller. It is both entertaining and revealing. I think the most interesting thing is that it shows good examples of how it can be possible to measure and evaluate processes which people typically consider impossible to quantify. This is a useful perspective, as measuring things is critical when to improve them.