Heres a simple way to keep your xbox 360 cool with some household items...
You will need:
PC Case Fan
XBOX 360 (Duh)
Cut the usb cable in half, splice the wires
Cut the 3 pin connector off the case fan, splice the wires
Connect the red wires to the black wires (from the fan to the usb cable)
Tape the wires seperately
Tape the fan to the BOTTOM of the xbox 360 with the air flowing IN the xbox 360 (your xbox must be sideways) if you need to put it on the back have it flowing OUT.
Plug it into your usb port on the xbox 360
If you have some other device with a usb port near your xbox, plug it in there. I plugged my fan into my verizon dvr. This is a good idea because its not gona ruin the xbox in any way.
If you have the xbox 360 standing the tall way (not flat) then put some rubber feet on the bottom so that the air can flow inside the bottom vent.
The fan runs slow. I havent figured out how to get it to go faster