I do a little bit of music production on the go with my Pandora. For this I use MilkyTracker and Sunvox, which can both be found on the repo. They're both trackers however, which may take some getting used to if you've never used one before. The only other music software I've seen on the repo is LMMS, which I frankly wouldn't bother with, and Qtractor, which I can't speak for because I've never tried it.