Just finished reading (and am going to reread) Reaching the Animal Mind: Clicker training and what it teaches us about animals By Karen Pryor. She does an excellent job of describing clicker training and the science behind it. She manages to do so without burying you in scientific jargon or simplifying it so much you lose the basic information. The book is full of interesting stories about animals she and other trainers have trained. She set up a website to go with the book that contains further scientific articles if you feel like tackling the science behind some of what she is talking about, other websites to visit, and videos of some of the different training episodes she describes.
I know everyone else has mostly posted fiction books, and I may have one or two to add later, but this book was really really good.
Dr. Seuss~DLH (brother's cat)~June 2007-
Misty~DSH (my cat & Mooby's mom)-?-
MooBoots(Mooby) ~ DMH(Mom's cat)~July 21, 2008-
Sunshine~ Golden retriever X white german sheperd (Dad's dog)~October 24, 2008-