Sleep Sound App - For those nights where you are in a hotel and need to drown out some noise or just want a calming sound to go to sleep to. The application would play music much like the sleep noise machines you can buy. For example it could play the sound of rain, waves crashing against the shore or rainforest sounds. It would have a sleep timer as well.QUOTE]
There seems to be an app for this...but I have not used or tried it. Just came across it last night while searching for something else.
MusicSleep (Demo Version) - Android app on AppBrain
Don't know about the different sound of rain etc...though.
There is also a paid version, for $1.59.
MusicSleep (Music Timer) - Android app on AppBrain