I think it would be very useful to be able to add a genre Level to the Music Library, or to be able to search by genre.
A second feature, that may be more complicated to add support for playlists. Play lists could be selected, created, edited, or played. To edit a playlist, the playlist would be displayed, you could then select entry, and either delete the entry, or insert a new entry after it. Adding a new entry would open a search and select dialog.