Star6 You can totally lose yourself in this sampler app. Using the included samples or add your own, mix up the loops with a variety of effects.

Bebot - Robot Synth It looks like a toy, but it's an instrument, too. Bebot is a retro-styled synth that lets you create theramin and other other trippy sounds.

BeatMaker A crazy-powerful loop and sequence editor. A bit clunky on the import and export of tracks, though.

Ocarina Love the idea of this app - turn your phone into a woodwind instrument! - but I don't have the skills to actually play it. It is cool to listen in on others playing around the world, though.

SmackTalk! Cute-overload animals repeat what you say in their squeaky little voices. For added fun, try burping loudly!