My neighbor and fellow consultant Theron just introduced me to the coolest iPhone application I've ever experienced. Its called the Ocarina, which is like a flute and the application is created by Smule. This application turns your iPhone into an Ocarina with the touchscreen acting as the wind instrument and your breathing into the microphone is the wind. It instantly produces beautiful music.
Here's the best part - you can link into people playing their iPhone Ocarinas all over the world. They can hear your music and you hear theirs. Now to get in tune!