I love Ina May's childbirth book! I'm reading her breastfeeding book now.
I have also read the following books that I recommend:
The Thinking Woman's Guide to a Better Birth by Henci Goer
The Birth Partner by Penny Simkin (for my husband, but I read it too and found it very worthwhile)
Pushed by Jennifer Block (if you want to know the research behind natural childbirth vs. hospital interventions)
The Baby Catcher: Chronicles of a Modern Midwife by Peggy Vincent (very enjoyable autobiographical book of birth stories from a Bay area midwife that is also informative)
The Complete Book of Pregnancy and Childbirth by Sheila Kitzinger
The Natural Pregnancy Book by Aviva Jill Romm
Birthing from Within by Pam England (not very informative, but helpful for examining your fears and attitudes)
Enjoy your reading!