I read...a lot. When I am passionate about something, I study and make it a goal to know as much on the topic as possible. This also means I recommend a lot of books, and I plan to share those recommendations as often as possible.
If you own more than a point and shoot camera, and you ever point it at people, you should read these two books.
Picture Perfect Practice
The author, Roberto Valenzuela, is as adept at teaching as he is at photography. One look at his portfolio will give you a good idea of just how skilled he is. These are not your typical photography books. You will not find them to be filled with diagrams, pictures and technical mumbo jumbo. Instead, you'll find concepts and theory and the real stuff that gets to the heart of being a true purveyor of your craft.
Think art. Think concepts. If you're looking for diagrams and recipes full of f-stops and guide numbers and light shaping wizardry-- you won't find it here. However, if what you're seeking is to hone your craft, to become a better photographer and not merely a good technician, this book is for you!
Picture Perfect Posing
If you only ever buy one book on posing, let this be the book.
Again, with the concepts. Roberto Valenzuela not only thinks deeply about his photography and his process, he clearly guides you (the reader) through the necessary steps to think as deeply about your work, and your images will be better for it. This is not a posing guide. This is a book that delves into the theory of posing. He doesn't provide you with images of poses for you to recreate your own stale versions of, instead he teaches you how to speak the "language" of posing, and how to use that language in various situations to achieve the results you're seeking.
What's your favorite photography book? Share with me in the comments!