Noizer - Ambient sounds like Noisli, but free
MyNoise - Custom shaped online noise machines. Many Many generic sounds
Defonic - Create a unique sound environment at home or in the office
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.
Studiowave - Chillout tunes and inspiration
Noizio - Feeling that the noise of the big city is too much for you to bear?