I really like PADI's Encyclopedia of Recreational Diving as a resource for new divers. Although the tone of the writing can be irritating, there is an enormous amount of good information in the book. I reread it recently for my DM class, and even now there was stuff in there (particularly the information about the oceans) that was new to me.
Mark Powell's Deco for Divers should be required reading for anybody who does more than a couple of cruise ship dives a year. Although in need of an editor, the book is a superb compilation of information it took me a couple of years to accumulate through other sources. And it's readable -- no math required.
Two other books are primarily for entertainment, but contain some definite lessons: Shadow Divers, which is a fantastic read, is a great education in the passion and dedication that people can show to their own niche in diving. And The Last Dive is about the same story, but from an entirely different viewpoint, and shows what having the wrong motives and the wrong approach can do to people in the diving world.
Have fun with these!
