We have been using our Mac mini a lot recently. In addition to the kids using it to play games, I am using it for iPhone development, and we use it to manage our photos and family videos. Since I keep it behind the monitor, it is a pain to get to the USB ports. I normally, just leave the cables for the USB devices connected to the USB ports on the back of the Mac mini, and just make the other ends lose and acceptible without moving items around. The problem with this is the Mac mini only has 4 USB ports. With the external hard drive, iPhone cable, standard USB cable for digital camera, there aren't enough ports for the mouse and keyboard.
So I went looking for a USB hub that would have the same footprint as the Mac mine. I found the Iomega MiniMax Hard Drive. This external hard drive has both USB and FireWire hubs. It fits perfectly under my Mac mini, and has allowed me to to everything that I have wanted.