If you've ever heard of frogg toggs' Chilly Pad, then you already know how cool the idea of a Chilly Pad hat is.
The original Chilly Pad is a towel that you wet with warm water and put it on you while you're in the heat. It holds 12 times its weight in water and the coolness lasts up to four hours. It gets 20 to 30 degrees below the ambient temperature.
The newest addition to the line is the Chilly Bean Cooling Hat. It looks like a regular hat but functions as a personal air conditioner. It retails for $12 to $15.