I rely heavily on the Internet for bird identification. This is mostly because I've yet to find a good comprehensive guide to Texas birds. There are some good general bird books, but I hate wasting my time thumbing through them when most of what I am finding is not what's in the area. I have 2 or 3 guides that concentrate on Texas, but each of them have significant weaknesses that make me reach for Google before I reach for them.
This weekend the luck changed. I wholeheartedly recommend Birds of Texas by Dr. Keith A. Arnold and Gregory Kennedy, published by Lone Pine Publishing (ISBN: 9768200189). Nearly 400 separate species are covered in detail with a single page for each. Outstanding detail on each of the species, as well as a description of similar species to help with identifications. Another 80 species or so are noted in pictures. There's also a 6 page checklist with just about every bird that can be found within the borders of the great state of Texas.
Why this book beyond others? The thoroughness of species is mind-boggling. Sparrows, as an example: There are 24 pages of sparrows. Another book on my shelf (which will likely now gather dust or become a donation) has only 6.
The only weakness: Hummingbirds. There are only 5 listed in great detail.
List price is $21.95, though Amazon has it cheaper. I got my copy at Waldenbooks in San Angelo and with my Borders Rewards semi-regularly distributed 25% off coupon, I got it with tax under $18.