55? Bah! Try Dan's Data Cooler Comparison. Not only does it list a huge number (over 110 Athlon coolers alone) but he's got the degrees per watt rating of each cooler, which makes it very easy to work out whether something's going to dissipate the wattage your CPU generates. He's also got reviews of water cooling and other bizarre equipment, and his testing process is very good. I recommend it.

Have fun,

Paul