It'd be nice if we could add items into playlists that aren't music tracks - just free text where you can leave notes to remind yourself of something, make a line separator to break up groups of tracks, etc.
You can use comments fields today, but those are stored in the track and appear in every playlist that includes the track. This feature would be useful for noting playlist-specific info such as transition plans, etc. It could also be a generic way to handle some of the other playlist management requests (such as reminders that "this track goes well with track X in this playlist")
I think notes would have to be attached to a specific track, so they would move correctly when the playlist was sorted or filtered. Maybe they could be implemented as an extra full-width "comment field" that appears above or below the associated track.
