My favourites:
New Active Birth (Janet Balaskas)
Spiritual Midwifery (Ina May Gaskin)
Babylove (Robin Barker) - I thought I would hate this one because it's fairly mainstream, but I actually like it. The author is very laid back about milestones (I've found other books seem to set unrealistically high expectations) and fairly gentle in her approaches to sleep.

I hated:
Contented Little Baby Book - I bought this one because I wanted to buy something on the 'routine' end of the spectrum. Bleugh! It has some seriously bizarre ideas that would only work for naturally calm and compliant babies.