Laptop Coolers

i dont have too much knowlege about this so im hoping someone can help me outmy friend has been telling me his laptop has been overheating a lot lately, so i would like to find a good laptop cooler for him, ive been trying to look up reviews but cant rly find a handsdown best, i did see a cnet comparison though.any advice / link to a good comparson page would be greatthanks in advance.