http://www.akaipro.com/synthstation49 or the Alesis IO Dock http://www.alesis.com/iodock or other MIDI interfaces for the iPad such as the iRIG http://www.ikmultimedia.com/irigmidi/features/ or Line6 Mobilizers http://line6.com/mobile#midimobilizer.
Using an external keyboard could greatly enhance note input.
![Wink ;)](./images/smilies/icon_e_wink.gif)