Experimental Homebrewing: Mad Science in the Pursuit of Great Beer, by Drew Beechum and Denny Conn
American Sour Beers, by Michael Tonsmeire
Perhaps the most useful homebrewing book, for both beginners and experts.
Yeast: The Practical Guide to Beer Fermentation by Chris White & Jamil Zanisheef.
The Compleat Meadmaker, by Ken Schramm.
Radical Brewing, by Randy Mosher
Clone Brews, by Tess and Mark Szamatulski
The Homebrewer's Garden, by Joe Fisher and Dennis Fisher.
Brewing Quality Beers, 3rd Edition, by Byron Burch.
Home Beermaking, 4th Edition: The Complete Beginner's Guidebook, by William Moore
Wild Brews, by Jeff Sparrow.
IPA, by Mitch Steele.
Malt: A Practical Guide from Field to Brewhouse by John Mallett.
North American Clone Brews, by Scott R. Russell.
The Homebrewer's Answer Book, by Ashton Lewis.
The Homebrewer's Companion, by Charlie Papazian.
Farmouse Ales, by Phil Markowski.
Extreme Brewing, by Sam Calagione.
Homegrown Hops, by David R. Beach.
How to Brew, by John J. Palmer.
Designing Great Beers, by Ray Daniels.
Brewing Classic Styles, by Jamil Zainasheff and John Palmer.
For the Love of Hops, by Stan Hieronymus.
Sacred and Herbal Healing Beers, by Stephen Harrod Buhner.