FYI, a frequent contributer to New Scientist magazine has written a well-reviewed book on the history and various applications of this long-debated subject. The original poster has undoubtedly received more than he asked for.
"Zero: The Biography of a Dangerous Idea, by noted science writer Charles Seife, starts with the story of a modern battleship stopped dead in the water by a loose zero, then rewinds back to several hundred years BCE. Some empty-headed genius improved the traditional Eastern counting methods immeasurably by adding zero as a placeholder, which allowed the genesis of our still-used decimal system. It's all been uphill from there, but Seife is enthusiastic about his subject; his synthesis of math, history, and anthropology seduces the reader into a new fascination with the most troubling number."