(http://thereifixedit.files.wordpress.com/2010/07/7a35efa9-478e-4ff9-a5be-a2987c603f1d.jpg)
Saw this on the usual site, thought it was relevant. Awesome idea in any case.
And I was going to suggest a wet hanky clipped to the front of a battery powered fan! ::)
Call me insane, but I wonder about the possibility of someone making such a contraption for commercial use. I know Zodi makes heaters that stay on the outside and vent into the tent (http://www.zodi.com/Consumer/zodihotventhp.html). However, it would be nice if someone could make a LP-gas air conditioner that would do the same, especially one that would have good insulation to minimize the noise of the compressor.