The iPhone Ocarina
Ocarina is app for the iPhone which trun your iPhone a musical instrument - ocarina. You just need to blow into the microphone, and play the four holes on the iPhone sreen.
"The ocarina is an ancient family of instrument (believed to date some 12,000 years), and one of the easiest instruments to learn. The Smule Ocarina both preserves this instrument and extends/transforms it for your iPhone. Blow into the phone/instrument. Control pitch with different fingerings. Learn to play countless melodies."