I apologize if this has been requested already. Couldn't find it in a search.

It would be really cool if I could see what Playlists a particular song is in.

I often go into the All Tracks soup view to find duplicates. When I find ones, I'm not sure which one to delete, since I really don't know what playlists each one is in.

Perhaps this could be implemented in one of tabs in the dialog box that comes up when you right-click on a song and select properties (such as information).

I also liked an idea suggested by somebody else where you could mark one of the duplicates as the one to keep, and it would delete the others and change all playlist pointers to the file that was kept.