The books I bought before getting a chameleon:
Chameleons: A Complete Pet Owner's Manual. Bartlett and Bartlett. Mine is 1995; I think there's a more recent edition.
Care and Breeding of Chameleons - Panther, Jackson's, Veiled and Parson's Chameleons. de Vosjoli and Ferguson, eds. 1995.
Since getting chameleons:
The Chameleon Handbook. LeBerre, Bartlett and Bartlett. 2000.
These first three are all broad, introductory, get-started kinds of books. Also:
Chameleons in the Garden. Lovein. 2007. Lots and lots of photos of wild Jackson's chameleons living on the Big Island of Hawai'i.
Stump-tailed Chameleons - Miniature Dragons of the Rainforest. Necas and Schmidt. 2004.
Chameleons of Africa - An Atlas. Tilbury. 2010.
Stump-tailed deals only (and thoroughly) with pygmies, including natural history as well as husbandry. Chameleons of Africa is mostly natural history, and not really how-to-keep-them. Very thorough (but excludes Madagascar species); not cheap.
And I like Lizards: Windows to the Evolution of Diversity. Pianka and Vitt. 2003, which is a good overall book about All Things Lizard.
Non-chameleon - I always like Terry Pratchett's Discworld series (kind of fantasy - there are dragons and magic - very funny, with very likeable characters).