I've got two 7 port USB hubs, one of which is completely full of stuff, while some stuff goes directly to the PC. Here is what I think I have:
1. USB DVD burner (I have a big tower on the floor with a DVD burner, but I wanted one within easy reach)
2. Web cam
3. 2 additional USB mini-hubs (1 on each monitor)
4. Recharge cable for Blackberry, PS3 controller, etc
5. Ink jet printer
6. Mouse
7. Keyboard
8. Saitek Pro Gamer unit
I used to also have a wireless Xbox receiver connected, and I also have a wireless receiver for a Logitech gamepad that isn't connected. I also have a few USB flash drives and a USB wireless NIC that I plug in on occasion, not to mention a fleet of USB hard drives.