Jam Player is a simple-to-use, yet enormously powerful app that promises to make learning and practicing songs a lot easier by letting the user seamlessly manipulate the tempo and pitch of any songs.
Simply load a song directly from the iTunes library, i.e. playlist, album, songs and artist. Direct access, no need to import or other steps.
Jam Player now works with Audiobus, you can record with GarageBand, and hundreds of other music apps.
More Information:
http://www.positivegrid.com/jamplayer