Laura Shanley's website
Bornfree! has lots of good articles/essays on it written by her.
Unassisted Birth, Free Birth, Jana Kutarna, excellent essay on her philosophy of unassisted birth
Maia’s Birth - a family celebration, by Sarah Buckley who also wrote the Ecstatic Birth article listed above
Birth, Sexuality, and Orgasm, Michel Odent MD, on the hormonal process of birth, and what interferes with it
Birth and the Origins of Violence, Michel Odent MD
Magical Child, Joseph Chilton Pearce. Okay, so he sometimes spirals out of control into the fringes of the weird and questionable, but some of it he is right on about, especially his ideas on the importance of acting in harmony with the natural matrix. This definitely influenced my philosophy of birth.
Reclaiming Birth for Our Daughters, Lesley Smith, unassisted birth is not mentioned, but it certainly applies.
Here are a couple of threads in which I've pretty much summarized my own UC philosophy, and are just generally good food for thought:
"UCers, wanna share your point of view?" (from MDC forums)
"Thoughts on UC" (from the Midwifery Today forums, NOTE:
please do not reply to this thread. For one thing, it is really old and would probably be received oddly, if not perceived as trolling. But more importantly, it's against MDC rules
(Violation: "Posting to invite members to other boards for debate purposes. This is to maintain and respect the integrity of our own and other communities.") and I'd prefer not to have this post removed and have to type everything all over again.

)