Gee, I think the books about the dangers of interventive care were the most helpful for me getting my mind all together and realize that taking responsibility for my own birth was the most important thing I could do for my babies
I loved Birth as an American Rite of Passage by Robbie Davis-Floyd. This is a great anthropological look at birth. I also found The Thinking Woman's Guide, Obstetric Myths vs. Research Realities, Immaculate Deception II to be helpful on my personal path.
Homebirth by Sheila Kitzinger, Choosing Waterbirth by Lakshmi Bertram (sp?) were also good. Spiritual Midwifery is also great for birth stories and confidence boosting. I'm not a huge fan of IMG, but SM is a classic
I'm sure I'm forgetting some really great ones....it's so exciting to be in the information gathering mode. Best wishes with everything!!!