[beachy]

My brother's house in Perth, Australia has an antique air conditioning system in the roof space that works in exactly this principle. 4 blankets that wick up water and have air drawn through them and into the house by a fan. It's in disuse now but I understand they were common and quite effective in the day.

[devilbunny]

They're usually called "swamp coolers" and are very effective iff you have very low ambient humidity. Utterly useless in humid climates.