I've got several relaxation CDs and some world music/drumming CDs that I plan to have on hand just in case I want them while in labor, but I understand I might not want anything -- it's different for each individual, I've heard, so I just plan to have them handy.
(Hehe I feel like I'm in college and planning a road trip -- gotta have my toys and tunes!)
Here's some of the ones I can think of off the top of my head:
Trance Planet Vol 2
Ayub Ogada
Earth Tribe Rhythms
Mickey Hart
Deep Forest (the orig one)
Assorted massage/relaxation CDs
maybe some various reggae for early on?
ditto w/Putumayo collections?
DH made the baby a mixed CD for Christmas that I've played for her in utero from time to time, so I'll have it handy too, but likely won't listen to it once heavy labor gets going, because I get distracted by lyrics too easily.
So that's why the CDs I have in mind don't have easily understood lyrics, or lyrics at all in some cases. If it's oh say African music then I don't have to pay attention to the words, just the sound. And I think that'll be better, but that's just me. I can't listen to "normal" music to go to sleep either -- I end up straining to hear the words. Does that make sense? I know we're not talking about going to sleep but I keep thinking labor's very trancey (as PP said) therefore I don't want to get distracted out of it.

So the drumming stuff is if I need rhythmic sounds and the relaxation music is if I need calming. But truthfully I think there will come a time when I'll just want the music off. But that's just me.