The Internet can be a cruel and unusual place. A place where anyone with some pent-up aggression can become a trivial sort of supervillain. With a little ingenuity—so little, in fact, that ingenuity hardly seems like the right word—an individual can make life miserable for others. Best of all for these Internet-gliding trolls, anonymity keeps their identity a secret. When I was in high school and the Internet was young, everyone had ICQ, the instant messenger that preceded Facebook...