I am a big fan of "Instructables", a site where people post detailed instructions on how to build something that they have made. There is some seriously geeky stuff happening there.
I found today that someone has posted very detailed instructions on how to build an air conditioner using a small cooler, a boat pump, and an oil cooler from a small car (he used one from a VW Rabbit).
You can find the whole story, with pictures, here:
-Steve Ballantion