The fact is the energy dispersed by water evaporating gives just as high a yeild as most of the tricks with alchohol, ice, or combinations. Its been beat to death, then we've reincarnated this particular horse, just so we can beat it to death again, then beat it when its dead, then start all over...
Just water (regardless of temperature) is fine. Cold water is slightly better... Alchohol takes ALOT of liquid to get the same effect as water, but can drop the temperature more if you just keep going for it. But unless you road race you don't have to worry about heat soak in our cars. I do it simply to lower engine temps while idling at hot autocrosses.
The engergy difference in 70 degree water and 33 degree water is minimal... its all in the evaporation and the 33 degree water dosn't carry enough energy to get up to 70 degrees to matter much. Now if you have an intercooler that isn't currently hot, its not currently being heated... say at a stable ambient temp, then alchohol can be misted (even chilled alchohol) and the ambient temp of the intercooler itself can be dropped considerably. Even moreso with NOS misters which can downright freeze the intercooler and really drop the charge temps like nobodies business. But for an autocrosser to take advantage of that they would have to mist/freeze right before they run and immediately shut their engine off after a run... I just don't see it helping that much.
Just a good garden sprayer filled with clean water will keep the radiator and intercooler nice and cool... and keep the car from cooking at idle. Drag racers... well those guys do all kinds of crazy stuff just for that extra 10th. More power to them.
Although it really wouldn't be that much work to run a new pump to put a switch inside the car I just don't think its neccessary. You'd get alot more use out of a small fan or an intake path sent to your intercooler in my opinion.