Water tank cooling strategies

Let's talk about cooling strategies. I've got my carboy in a plastic tub of water, but the ambient temperature of the apartment is high enough that it gets to around 76 (tub temp) if I'm not careful, and 70 overnight if I've put some ice in the tub. I can keep it at 62-66 (the temp I want) if I continually rotate ice. It takes three pint-sized plastic yogurt containers to drop the water from about 68-70 to 62, which isn't bad.

My problem is that I'm not really able to continually add ice through the course of the day, most days. Has anyone built anything that might keep the water chilled? I was even thinking of checking out one of those stand-up water coolers, and trying to take apart the cooling element or something. Anyone experimented with thermoelectric cooling? I'm up for building my own thermostat, too--I've got some microprocessor skills—but I can't figure out a good way to keep that volume of water cool.

Okay, not really an issue 3-4 batches from now, in the fall, but a perpetual issue in the summer. I just brewed a pale ale with PacMan yeast that tasted suspiciously like a grapefruit wit (strong grapefruit flavors from the amarillo hops, wit from the 74 degree fermentation temps). Any tips?

Have you tried making a "swamp cooler?"

When it is in tub of water, wrap your fermenter with a wet t-shirt and point a fan at it. This method used evaporative cooling to lower the temp of fermentation.

Yeah, I've got that going. That only works up to 100% humidity, though--this guy is in a little side closet and in this weather (June in a tiny NY apartment) I couldn't even manage to get it down below 72 with a fan and t-shirt. Ice is required.