A couple weeks ago I saw the Antec Notebook Cooler mentioned in a magazine a couple weeks ago and it set off my Spidey geek gadget sense.
I ordered the cheapest one I could find online (about $27+shipping), and it arrived a couple days ago. So far, it works as advertised.
Normally, just a couple of hours of normal use has my laptop heating up like a microwave oven. Really intensive computing moves it into blast furnace territory.
With the Antec Notebook Cooler, the underside of the laptop remains cool to the touch even under the most intensive usage. I had it run for about four hours doing some intensive processing of video files, and the temperature remained suitably low (typically, my laptop would become warm enough that top surface would begin to warm after that).
The Notebook Cooler as two fans in it, and it draws power by plugging into a USB port (the USB cable is pass-through so you are not wasting a slot).
The only real drawback is the extra noise. Personally, that is not a big problem for me, but your mileage might vary. Also, this is clearly a solution aimed mainly at those of us (like me) who use our “laptops” largely as portables — you would not want to actually use the notebook cooler on your lap. It probably will also shorten battery life, but I rarely run my laptop off the battery anyway.
So, if you are the sort of person like me who uses their laptop computer largely as a portable between fixed sites (my laptop spends 95% of its time on either my home desk or my work desk).