It would be really nice to be able to view the score of the project (i.e. the musical notes on a staff) and print it. The piano roll is close, as far as seeing the pitch and rhythm, but a way to view and/or print actual music notation would be nice. This would allow a more compact viewing by those who can read music.
Note that I'm not saying there needs to be the ability to do editing directly on the score view -- the piano roll does that very nicely -- just the ability to view/export/print it.
Email: source@oatmeal.afewmoore.net