See, despite the absence of user names, a number of people had unknowingly identified themselves by way of "ego searches." That means that, along with searches for pleasant topics like rape, murder, committing rape and murder, hiding rape and murder, and Clay Aiken CDs, they also searched for their own names, addresses and social security numbers.
Within days, The New York Times had released, with consent, the name of a user who they tracked down by cross-checking search keywords with phone books and other public information. After a few weeks, AOL had not only fired the researcher responsible for the leak, but also his supervisor and Chief Technology Officer Maureen Govern.
All because of one click of the mouse.
As a bizarre postscript to all of this, one of the users identified in the file only by number ("User 927") became internet famous for having basically the creepiest search habits imaginable. Searches included "human mold," "dog sex," "child porn," "Disney Beauty and the Beast Porn" and, most frighteningly, "'Sugar, We're Going Down' by Fallout Boy." No, really.
Well, recently, a stage production premiered, based on their life, called User 927.