A Soft Murmur - Ambient sounds to wash away distraction.
Noizio - Feeling that the noise of the big city is too much for you to bear?
Rainy Mood - Rainy Mood is the world's most popular rain simulator. Sleep, study, and relax with the sound of rain.
MyNoise - Custom shaped online noise machines. Many Many generic sounds
Calm.com - Calm.com can help you reduce stress and increase calm.
Noisli - Noisli is a fantastic background noise and color generator for working and relaxing. Online soothing ambient sounds like White noise, Rain and Coffee Shop.