I just discovered NatureSpace [http://www.naturespace.com/]. They call is "Holographic Sound", and its pretty amazing. Check out their website (there is a preview on their landing page, and I strongly recommend having a pair of stereo headphones/earbuds on ;-) )
They have a free iPhone app, well if you have an iPhone, and want to try it out.
[Update - Seems they have options for the Android too]
They have a free iPhone app, well if you have an iPhone, and want to try it out.
[Update - Seems they have options for the Android too]