If the soreness of one's writing hand is a gauge of literary success, Indy-based novelist John Green is on a tear. He recently inscribed every copy of his new young-adult book, The Fault in Our Stars (Dutton Juvenile), out this month, and needed steroid treatments to sign all 150,000 autographs. "When I did a bad one, I wrote a secret URL on the page that takes you to a video of me apologizing for the bad signature," says the 34-year-old, who has a huge fan base online. Half a million people subscribe to his YouTube channel, Vlogbrothers, on which Green and his brother Hank do stuff like perform Star Trek parody songs and discuss the travails of the writing process. Like Twihards and Gleeks, their fans even have a nickname: Nerdfighters.