My laptop, a Dell 5100, gets real hot when I leave it crunching 100's of megs of XML for extended periods. The fan puffs hard but not enough to keep the thing cool. In full throttle, you could fry an egg on the back of this thing.
When the heat gets too much for it, the laptop spontaneously shuts down with no warning. No messages in the logs saying "too hot, I'm outta here". Nothing. This can be real annoying when you leave a machine running on some big data processing task overnight only to find out in the A.M. that it shut itself down at 12:30 a.m..
Anyway. I solved the problem by raiding (appropriately) the oven in my house. Note the indispensible domestic item under the laptop.
Works great. 72 hours and counting :-)