As little as possible, but I have an extreme weakness for the Oakland A's, Ray Fosse cards and ridiculously awesome non-sports cards from the 70's and 80's.
Someday I may keep track of my collection on here and do some trading but sometimes it's better to not know how many cards you actually have. There's a fine line between having a collection and having a problem. In the meantime, I'm a lurker on the site who is grateful for such a fine reference source to help me figure out what the hell these card companies are cranking out nowadays.