As one commenter quotes Ned Flanders, "There's no justice like angry mob justice."
A 16-year-old New Yorker, Sasha Gomez, made the unfortunate choice to steal the phone she found in the back of a cab. The victim had to buy a new phone and when she logged into her account, she found pictures of Gomez along with her AOL screen name, as Gomez hadn't been a criminal long enough to know that you don't put your name and photo on shit you steal.
A friend of the victim, Evan Guttman, tracked down the thief and sent her an IM asking her to return the phone, to which he was politely told to jam his head in his ass and see if he could look out his own mouth again. All Guttman did in response was to make a simple webpage that included the pics of Gomez and a description of what happened. These things always start small...
Next the page was linked on Digg, and Gizmodo, and from there to hundreds of other sites. Hundreds of thousands of people read the story, remembered the last time they fell victim to some asshat with sticky fingers, and started a massive virtual campaign of harassment against Gomez. People from all across the planet were sending e-mails, some of them likely with the most strongly worded LOLcats you can imagine.
Of course this wasn't nearly enough for the more industrious types who tracked Gomez down on MySpace and started to harass her and her friends. Then it was time for the real hardcore avatars of justice (or the insane) to bring it into the real world, actually finding her address in Queens and driving past her home shouting accusations and 4chan memes.
Eventually the thief's brother--a military police officer--got involved and told Guttman to back off, which at this stage would be like telling to butterfly to stop the hurricane it triggered. This incited a new shitstorm and earned the brother a reprimand from his military bosses. Before the situation could get out of hand and martial law declared, the thief gave up and turned in the phone. She was arrested and the story was added to the annals of cyber-mob justice.