Charles Stross - Rule 34

"The most spectacular science fiction writer of recent years" (Vernor Vinge, author of Rainbows End) presents a near-future thriller.
Detective Inspector Liz Kavanaugh is head of the Rule 34 Squad, monitoring the Internet to determine whether people are engaging in harmless fantasies or illegal activities. Three ex-con spammers have been murdered, and Liz must uncover the link between them before these homicides go viral.