According to NetCraft, several sites referred more traffic to troll attacks in progress than any other sites on the internet. When researchers went back to the sites in question, they found trolls organizing themselves to destroy the target sites.
Here are the top five troll sites on the internet:
If you see these sites in your logs at the same time you get a sudden spike in traffic, you should investigate it. Trolls specialize in posting anything that is perceived as socially offensive, yet has a grain to truth of it -- giving it the controversy they thrive on. Heading them off at the pass can stop your site from becoming an unending flame war.