RealBeat is a mobile app for iPhone that lets you record sounds in your evironment and mix them to create music. Designed by independent developer Joerg Piringer, the app lets you record, cut, loop, and sequence sounds. You can also modify sounds and add effects, and export finished music via Audio Copy or iTunes. The app is available in the iTunes store.
For more information on RealBeat, visit http://apps.piringer.net/realbeat/.