"Many trolling practices, like prank-calling the Hendersons and intimidating Kathy Sierra, violate existing laws against harassment and threats. The difficulty is tracking down the perpetrators. In order to prosecute, investigators must subpoena sites and Internet service providers to learn the original author’s IP address, and from there, his legal identity. Local police departments generally don’t have the means to follow this digital trail, and federal investigators have their hands full with spam, terrorism, fraud and child pornography. But even if we had the resources to aggressively prosecute trolls, would we want to? Are we ready for an Internet where law enforcement keeps watch over every vituperative blog and backbiting comments section, ready to spring at the first hint of violence? Probably not. All vigorous debates shade into trolling at the perimeter; it is next to impossible to excise the trolling without snuffing out the debate."

A huge list of brands on Twitter.