Here's a list and a small review of what I found helpful from each book:
The Thinking Woman's Guide to a Better Birth by Henci Goer and Rhonda Wheeler
This is by far the best book I have read. A little clinical and boring at times but full of very helpful information. A must read and a real eye opener.
Birthing from Within: An Extra-Ordinary Guide to Childbirth Preparation by CNM, MA, Pam England and PhD, Rob Horowitz
This book definitely has a very new agey slant to it but there are some very helpful thoughts to be gained from reading it. For me, I really enjoyed the chapters on birth art and working through your fears and negative experiences in giving birth.
Natural Childbirth the Bradley Way: Revised Edition by Susan McCutcheon-Rosegg, Erick Ingraham, and Robert A. Bradley
Jeremiah and I read this book together when we were preparing for our first child's birth. Practicing the relaxation techniques was enjoyable and I gained some helpful information. I suppose if you had a long and drawn out labor, the Bradley method could be invaluable. Because my labor was so short and quick, we didn't do a single thing we had practiced.
Supernatural Childbirth by Jackie Mize. This was a gift from my mom and I honestly only briefly read through it. I found the scriptures helpful to meditate on but the basic premise of the possibility of having a pain-free childbirth a little on the flaky side of spirituality. I believe birth is supernatural but I also believe that pain is a part of the process.