If you're looking for soothing tracks to help your sleep or fill your work space, Sound Sleeping offers you the ability to mix your own custom track.
You can mix five different sounds including outdoor sounds like rain, ocean surf and crickets chirping, as well as man-made sounds like drums and bonfires. Each source sound can be panned left and right and adjusted in volume. With some careful sound selection, you can make some interesting effects. The screenshot above shows the positioning for a loop that recreates the effect of sitting on a beach with ocean to one side and a drum session/bonfire to the other.
If you're more interested in relaxing and less interested in fiddling with the tuner, there are quite a few premixed tracks available for download at reasonable prices.
Know of a great place online to find soothing sounds? Share the nerve-calming wealth in the comments. Thanks Rick!