Any of the Rockabye Baby albums - those people are geniuses. My colicky baby that cries 9 hours a day is soothed by this (sometimes...if something will make her stop usually this is it).
White noise works like a charm for our LO. We sleep with the bathroom fan on and raining crickets. It always sounds like we are camping in our bedroom. I actually like it too. Lullabies during bedtime routine.
My girls love Disney Lullabies and Jewel has a childrens CD that soothes them. I also have a ton of baby einstein music downloaded onto my ipod and i just hit shuffle and play all 3 of those cd's all day.
When I was about 34 weeks my baby was breeched, so I tried the method of playing music on my iPod withe the headphones toward the bottom of my tummy and I guess it worked cause she was head down afterwards. The music I played we're mostly classical cause they are quite calming and soft. I especially love Pachbel canon in d major. My lo does too because when she hears it she knows it's bedtime and falls asleep within 10 mins.
Re: What music helps your baby sleep?
Gillian Welch - Miner's Refrain
Old Crow Medicine Show - Wagon Wheel
Neither are "baby" songs but both are very calming to him
Graco sound machine, I use the heartbeat sound every night to start a routine so DD learns that when she hears that then its sleepy time.
I think it works better for me than for DD sometimes!