I am eating soup and typing with one hand, but this topic deserves an immediate reply...
Have always collected things: books, CD's,
(good, I cleared a space to set the soup down, now I can get back to 90 wpm typing)
pens (costly habit), recently guitars (even more costly than the pens I collected), and now cameras (always interested in photography since my teens, and practicing it much of the time, but never collecting cameras before).
My interests fluctuate a lot, with several remaining constant but "rotating." I have about 600 CD's, over 700 LP's, about a thousand books (got rid of MANY last time I had to move), four guitars (I hope that's over with), three cameras (don't mind that so much).
I'm discovering how to have fun posting photos to flickr.com and enjoying others' photos there. This is a good thing for me because it can be truly absorbing and helps with my generalized anxiety and worry--they disappear briefly while I'm doing photography.
My collecting, like that of several others posting here, might not seem truly "collector" collecting, as I acquire things with a view toward using them, whether I end up doing it or not. But I feel like a collector most of the time, and I guess that's what counts in the end.
EDIT: I thought of two things to add. I also collect Buddhist rosaries. And regarding CD's, LP's, and books, I MUST have complete sets of everything that comes in more than one volume or disc. If I have only found volume two, for example, I will not buy it. It makes me deeply unhappy, and strangely uneasy, not to have the "complete" whatever it is. I feel almost as though the few items I do have that are lacking their companions, contaminate my collection in some way. So I try always to avoid buying something incomplete.