I like David Zeller, and he is very relaxing. He makes all his music with birthing women in mind, and many are lulabys and whatnot.
Hes out there online, googling him should just bring him right up. He has 3 cds I think, 2 are mostly in Hebrew, which may bug some mammas, but one I think is mostly English.
Its also good for after a birth to unwind youself!