It cracks me up that other people think about this stuff. For a long time I've thought about making a insert to a window so I could pull air in from the outside, and then exhaust it back outside. living in Denver means that there are several long months where I could pull in some really chilly air.
Of course I'd have to be careful about how cold the air was how humid it was (condensation = suicide). the construction of such a thing could be really rudimentary and easily done, I just never did.
