Home sick this afternoon, I finally watched a DVD I've had laying around: "Orgasmic Birth." For the most part, it's kind of low-budget and repeats a lot of what's said in "The Business of Being Born," so I can't recommend it too highly.
HOWEVER, there is a woman in it who is shown having not one, but TWO, orgasms whilst giving birth. WOW. Her labor and birth experience are shot on film and included in the film--it's hard to believe, but seriously, you can tell it's happening to her, for real. I thought it must be faked, or maybe a re-enactment for film, but no, this mama's eyes roll back into her head with pleasure! It's incredible.
If I get pregnant, I plan on doing some serious research into this possibility.