Philosophy Pages: Niccolo Machiavelli (1469-1527)
http://www.philosophypages.com/ph/macv.htm
A brief bio, a list of useful sources, and several links.
The Seven Books on the Art of War
http://www.marxists.org/reference/archive/machiavelli/works/art-war/index.htm
The entire Art of War - a treatise Machiavelli wrote after The Prince.
Niccolo Machiavelli - The Prince
http://www.the-prince-by-machiavelli.com/
A site devoted exclusively to The Prince, with a detailed summary, pictures, and a page of colorful quotes. Plus, online text of The Prince, translated by W. K. Marriott.