Moodwill - Create and listen for free to your perfect nature sounds environment with music to help you concentrate, relax, sleep and overall feel better.
Noizio - Feeling that the noise of the big city is too much for you to bear?
zenmix.io - Ambient background sound generator
Noizer - Ambient sounds like Noisli, but free
Defonic - Create a unique sound environment at home or in the office
Studiowave - Chillout tunes and inspiration