I recently got a set of Cool Feet from Bluelounge. Cool Feet are essentially rubber suction cups that you attach to the bottom of your laptop to elevate it, allowing the heat generated by the system to disperse (see image below), whereas without being elevated the heat would be trapped between the system and the desk (or whatever surface it’s placed on).
I’ve used the Cool Feet for a few days now and although the system’s reported temperature is about the same, the fan hasn’t come on as often as before. Before using Cool Feet, periodically the fan would spin up from it’s idle rate (2000 rpm) to a higher spin rate (~5000 rpm) sometimes even reaching it’s max spin rate (6200 rpm). So I would say that although the Cool Feet don’t lower the actual temperature of the system, it does help ventilate the heat and overall does keep the system cooler.
Although there are other cheaper alternatives then Cool Feet, such using two rubber erasers or cardboard, I think Cool Feet is worth the investment. Since they’re attached to the system through suction, if you have a sudden need to slide the system forward or backward a bit they’ll move with the system; where as cardboard won’t and erasers only move with it sometimes. Not to mention you can pick up the system move it to another part of desk with the Cool Feet still attached so you don’t have to worry about repositioning them to the setup you want. Overall, I would have to say it was money well spent!