Pianos are expensive. After seeing the Leap demoed at the hackathon, we created a small virtual piano that can be played using only the Leap and your hands.
This was all of our first times using Unity and its APIs, as well as our first time using the Leap, so getting the exact physics of the piano down took quite a bit of time. With our last version, you can pretty accurately hit the keys.
We hoped to add a learning mode that would highlight the keys as they were played in real piano recordings, but didn't have time to finish.