If you haven't read "Noah's Garden" by Sara Stein or "A Sand County Almanac" by Aldo Leopold, I highly recommend them.

These books are not specific how-to books for attracting wildlife, but I think they are a great read for anyone interested in gardening for wildlife.

I also like "Natural Landscaping" by Diekelmann. Its more of a landscape design book. I refer to it, from time to time.

The sequel to "Noah's Garden" is called "Planting Noah's Garden" and has some how to tips for native planting which should help increase native wildlife.

"Bringing Nature Home" is another good one if you consider bugs to be wildlife.

The Wild Ones web site might help also: http://www.for-wild.org/

Here is a link that might be useful: Bringing Nature Home

Here are what I'd recommend in order and why (2 have already been mentioned):

1. "Bringing Nature Home" is important even if attracting bugs isn't your aim, as long as you can tolerate them. There's another thread on this forum that I've linked to that includes a New York Times article about the author of that book and will give you a quick idea of what the book is about. Lately when I read books on wildlife gardening I get a few new ideas. This book was much more informative for me, and gave me concrete reasons that native plants are ususally the way to go for the most part for wildlife gardening.

2. "Noah's Garden" was informative when I was just starting to do habitat garden, and again when I reread it recently

3. "Native Trees, Shrubs, and Vines: A Guide to Using, Growing,and Propagating North American Woody Plants" and
"The New England Wild Flower Society Guide to Growing, and Propagating Wildflowers of the United States and Canada" by William Cullina aren't directly about wildlife gardening, but I've found them very useful in choosing plants. Although the information about wildlife benefits is far from complete, I've found what is there useful

Here is a link that might be useful: To feed the birds thread

I have a couple books I really like.
"Your Backyard Wildlife Year" by Marcus Schneck
"Natural Landscaping" by Sally Roth
"Gardening for Wildlife" by Craig Tufts and Peter Loewer

Besides the ones mentioned by Loris (all excellent), I'd add :
"Birdscaping Your Garden", by George Adams
"Attracting Birds To Your Backyard", by Sally Roth
"Native Alternatives to Invasive Plants", by C. Colston Burrell
"Taylor's Guide To Natural Gardening" edited by Roger Holmes
"American Wildlife & Plants : A Guide To Wildlife Food Habits" (very old--1951--but still very useful.)
"The Audubon Society Guide To Attracting Birds", by Stephen Kress (Other than recommending some aliens--it was written in 1985- it's just a superb book. Just don't plant anything he identifies as alien.)
"Teaming With Microbes: A Gardener's Guide to the Soil Food Web", by Jeff Lowenfels & Wayne Lewis (The best rationale for going organic - which all wildlife gardens need to be - and a wealth of info on how to restore health to your soil.)
And for anyone living in New England, my all-time favorite, my most thumbed-through book, is "Native Plants of the Northeast" by Donald Leopold

Someone else mentioned her, but I just want to reiterate how wonderfully inspirational Sally Roth's book, Natural Landscaping, is.

I have most of the books mentioned by the other posters, but this is the one I return to over and over again--especially in the winter when I've got the "Locked in the house/Old Man Winter blues."

Roth's voice and narrative are informative and friendly, and her passion for her wildlife gardening imbues every page. The photos are gorgeous, too.