The JustCooler works really well. Under our testing conditions, I noticed up to a 10 degree (F) drop in temperature when measured on the surface of the drive. Not too shabby when you consider the size and cost of the unit. I also noticed that the cooler helps to reduce overall system temperature. When we measured the temperature between the AGP and 1st PCI card, the cooler made a difference of 3-5 degrees. Considering that this is a hard drive cooler, and not intended for case cooling, it was a nice extra bonus.
Where the Super Cooler really excels is in heat monitoring. Gauging the accuracy of the heat measurement against a several thousand dollar thermal sensor, we found that the Jameco Super Cooler was much more accurate than the RadioShack Indoor/outdoor thermometer. In some cases, the RadioShack unit was off by as much as 15 degrees F while the Super Cooler was never more than 4 degrees different than the thermal sensor.