Heh! I was wondering if anybody was going to mention WaterWetter...
WaterWetter is made for racecars, e.g. for racing on tracks that do NOT allow you to use antifreeze, for safety reasons. Basically, what it does is make small bubbles instead big bubbles, when water BOILS, i.e. it keeps big bubbles from forming in the first place.
You see, racers know air is a poor conductor of heat -- just like 'us'. If you've ever boiled water in a pan (or overheated your car), you know how big these bubbles can be -- and these big bubbles don't do jack for cooling. The fact of the matter is, they keep the water from doing its' job.
Accordingly, small bubbles allow more water to get to the surface in water 'jackets' (where the bubbles themselves are actually produced), effectively making the water wetter, hence the name...
Having said all that, if you ARE running antifreeze in your system, and/or the water is NOT boiling AND producing big air bubbles -- I do NOT see any reason to use WaterWetter in a PC environment. Au contraire...
The 'bad part' about WaterWetter -- the downside -- is its' pH is right off the scale (no pun intended). It's okay if you don't use MUCH of it (1:32 if I remember correctly) and you dump and restore it every once in a while, however, it's really not a nice substance. I don't *know* what the longterm effects are to the pump, blocks, and radiator in a PC, et cetera, but I highly doubt that's it 'good' for them.
Bottom line: I judge WaterWetter to be a necessary evil for certain applications (emphasis on evil), such as sanctioned car racing, but I wouldn't put it in MY computer... No way!