The Nyko Intercooler is a possible solution, since it keeps your xbox cool. This cooling unit plugs into the back of your 360 using the 360's power supply. However, there's an ironic problem. The Nyko Intercooler is also badly designed ... and also melts. The problem is that the 360's power supply at times uses so much juice that the Nyko's adapter melts.
Also, because the 360 wasn't designed to power a separate set of fans, it sometimes does not get the power it wants and games crash. Bummer! (happened to me within 5 minutes of use without this mod).
The obvious solution is to rig it to use it's own power supply! My method involves getting an AC/DC adapter so that you can get juice from your wall. I found another design that uses 12v batteries. [link]
http://forums.xbox-scene.com/index.php?showtopic=602647&st=0[/link]. I personally prefer my design, because you don't need to worry about getting new batteries all the time!