pick which tracks on albums?

Hey, what about adding a feature where you could check off which tracks of an album you have. For those of us who have acquired tracks from albums without owning the whole album, this would be super useful. Perhaps the default would be that all tracks are checked so that this doesn't interfere with others, but for those of us who only have a few tracks, we could uncheck the tracks we don't have and check them in if we get them later. What do people think?