Available for athletes who need to keep cool on hot days, ice vests use, well, ice packs packed in a vest or a shirt to cool a body. DIYers over at Ecomodder have been discussing using ice shirts in cars and other homebrew alternatives to avoid cranking up the AC. A real cursory search finds commercial ice vests available in the $90 to $220 range. More options on the Ecomodder discussion block include beaded seat covers (for more airflow behind the body), portable AC units, and window tinting. Thanks to Darin for the tip!