I'd like to present you Pianolo HD for iPad. This app is a multi-touch application for your iPad. You have the possibility to play six different musical instruments (grand piano, violon, organ, saxophone, guitar, electric guitar) on your device. There are also some nice multiplayer-parts: A Four-Octaves Piano-Multiplayer, A 2-Player-Piano-Mode and a Piano-Saxophone-Multiplayer-Mode. I'd be happy if you would have a look on my App and give me some feedback.
Here are some screenshots:
Best regards and thanks for your help!