The Cool Shirt is a t-shirt with a clever water cooling system for your body. If you are familiar with water cooler designs for computers, then this one will look quite similar. There is an inlet and an outlet on the fifty feet of rubber hose that connect to a pump. The water circulates and you get to sit in the furious heat of summer without feeling the effects and without resorting to air conditioning.
It is designed for car use and is actually for racing car drivers, but I don’t see any reason why you couldn’t rig one of these up for home use; all you need is to take your water container indoors and use a pump with a suitable power source. If you went so far as to cannibalize the cooling system from a water cooler (the drinking kind), you could keep yourself cool indefinitely, though with a slightly greater environmental footprint.
I have no idea of the price of the Cool Shirt, but considering that it is for a very limited market, I would say that it is likely to be expensive. If you have the time, inclination and are handy with a sewing machine, there is no reason why you could not construct your own. All it is, really, is a tight-fitting shirt with some rubber hose stitched to it attached to a water pump. You could work wonders with some aquarium parts. [Stock Car Racing via Crunch Gear via Ubergizmo]