HardwareSecrets compares thermal pastes, you can check it out over here.
HS added five more new thermal compounds to our previous roundup, for a total of 25 different thermal compounds from major brands. We also tried an "alternative" compound: lipstick.
Here is a snippet:
"Following up on our Thermal Compound Roundup - May 2011 review, we are adding five more thermal compounds to our roundup, for a total of 25 different models from Antec, Arctic Cooling, Arctic Silver, Biostar, Cooler Master, Coolink, Deepcool, Evercool, Gelid, Noctua, Prolimatech, Scythe, Shi-Etsu, Spire, Rosewill, Thermalright, Thermaltake, Titan, Tuniq, Xigmatek, and Zalman. In this review we will determine if certain products are superior to others. We will also try an "alternative" thermal compound to see if it works."