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.
Blanket - Improve focus and increase your productivity by listening to different sounds. Or allows you to fall asleep in a noisy environment.
MyNoise - Custom shaped online noise machines. Many Many generic sounds
Calm - Calm.com can help you reduce stress and increase calm.
Noizio - Feeling that the noise of the big city is too much for you to bear?
Tide (by Moreless) - Tide - Sleep Sounds, Focus Timer, Relax Meditate - Be calm and mindful with nature.