Right now, my Cannondale is in the dining area, my Triumph is in the bedroom on the work stand, my Bianchi is in the hallway, and my Kona is in my storage locker in the basement. (Keep in mind that I live in a one bedroom apartment!) I have two other frames that are currently in a friend's basement with primer drying on them. The most I have kept in here at once was 5 bikes...

I'm moving to a different apartment in a week, though, and I won't have a storage space in the basement anymore. It is also a small one bedroom, so I'm probably going to invest in some kind of vertical rack like what cuda2k mentioned.