One of my friends is up to 6... and he'll finish building the 7th when he finds a fixie hub. Each one is for different riding types, too.

I hate to admit it sometimes, but I'm only at one, although I've got 3 more picked out just in case I have an unknown millionaire uncle die and leave me his fortune. Then I just have to figure out how to fit a Trek hardtail, Intense Spider, Trek 5200, and Redline Monocog in my dorm room.