I found "Mathematics for the Millions" (http://www.amazon.com/Mathematics-Million-Master-Magic-Numbe...) to be a very interesting read. It goes through the history of math, how it was discovered and used, from ancient Egypt (geometry) to the 1600s (Calculus) and shows the progression of thought.
Seconded. "Mathematics for the Million" is an incremental, bottom-up approach to learning Mathematics. It should be an interesting read for those fond of history.