There is a good soundscape generator called Atmosphere Deluxe. There are a couple of good noise generator software out there. Noise Maker knows a lot more but BrainWave Generator is just perfect. You can synthesize very soft pink noises by setting noise smoothless above 90%. Or you can play it into wav, and modify the spectrum profile on fly through Winamp’s equalizer for better results.
Noises have more than just a calming effect on the mind, they actually puts the body into sleep by boring off the brain. I have been experimenting with spectral shaped noises. Apparently this technolgy has great potentials in altering consciousness. By amplifying the power of specific freqency bands they could push and pull consciousness along its axis, even provide some sort of energy to the brain. The fun thing is that, in theory, it should work for the deafs, too, so you can use earplugs. Be careful though with those earplugs! They are very dangerious.