You might think that a computer housed in corrugated cardboard is something for hobos to do their taxes on, but that's not the case. Cardboard is actually better at dissipating heat than plastic, and it acts as a sustainable and efficient casing for your desktop computer.
The Recompute cardboard computer lets you put what you want inside, but it has 8 USB ports and room for all of the guts that you'd find in your traditional computer. It works in both horizontal and vertical configurations, depending on how you like to have your setup. The only real trick is getting over feeling like a hobo while you're using it. Give it time.