18. Judy McGrath
MTV Networks delivers more than half of parent Viacom's sales. Revenues in McGrath's division rose 7% last year, to $7.2 billion, and operating income 11%. But youth culture is fickle, and MTV's buzz has lessened since her mentor, Tom Freston, was fired in 2006. McGrath has her reputation for cutting-edge creativity riding on two projects: a social networking platform, Flux, and an investment in VBS.tv, the online video offshoot of hipster magazine Vice.