I don't really collect anything in particular -- more of an "if I want something, I get it" person, but what I want doesn't tend to lead to me collecting a lot of any one sort of thing.
I have a few DVD'd TV shows and movies, but not enough to be a collection (more cheap-ass horror films than a sane person would have, but not enough to say I have a crap cinema collection, for example).
I might be able to say video games, since I have a large backlog of games I haven't even started yet, but I wouldn't call it a collection because it's nowhere near as large as it'd be if I hadn't traded in so many back in the day. If I kept everything I'd ever bought, I'd have a few hundred laying around the house. Probably have at least 150, but that includes all my old Atari 2600 and NES games I have in boxes because the actual systems no longer work.