Moszen - Moszen is a free web service that provides ambient sounds from natural environments to help you relax and avoid stress in your daily life.
Headspace - Meditation made simple. Brilliant things happen in calm minds.
Noizio - Feeling that the noise of the big city is too much for you to bear?
Calm - Calm.com can help you reduce stress and increase calm.
Sleep Bug - Sleep Bug is the name of an ambient sound mixer that generates a wide range of scenes and music using the random sound effects.
Mezmind - Calming Interactive Environments