I can’t get a link because I found it on itunes, but there is now an app called “Inception - The App” That’s apparently like a game, and you unlock soundtracks and such, some which induce lucid dreams.
I found it looking through the app store in excitement as I just bought an iPod touch of ebay, so this will defiantly be the first app I download!
My brother has this app on his iphone. Basically what it did was distort incoming sounds from the world around you and plays it through your headphones. To be honest most of the settings sound really cool!