We love these detailed DIY instructions from Hack College (by way of Lifehacker) to make your very own dorm-legal air conditioner from a floor-standing fan, copper tubing and some buckets. Or check out the instructional video below for the full 'how-to.'
The whole rig might sound dinky, but it "will cool even the hottest dorm room to a nippy 60 degrees Fahrenheit in no time." Sure it might be a bit unsightly, but so is everything else in your dorm. At least it gets the job done cheaply.