Snakes: The Keeper and the Kept and Snakes and Snake Hunting, both by Carl Kauffeld, absolutely classic reads. A must-have for any herp library, as they herald back to the early days of captive herpetoculture.
Snakes: The Evolution of Mystery in Nature, by Harry W. Greene. Well written, interesting read on what snakes are and how they work, and how they're woven into human culture. Great pics & although the text can be somewhat technical, it moves along at a steady clip.