Now that we've renamed collections to lists and given people the ability to make as many as they like with whatever names they like, it would be nice if we could somehow specify what sort of list it is, e.g. a list of things you own, a list of things you want or some other sort of list. VGMdb also has a "for sale" list, giantbomb.com apparently also has a list of favourite things.

If we know which lists are of things people own, we would be able to do things like say on the release page how many people own it (like requested in http://bugs.musicbrainz.org/ticket/4061 ) or how many people want it (like Discogs/VGMdb do) or even make stats pages about things like the most owned/wanted releases.