What makes a great broadcast interviewer?

Larry King's radio and then TV shows have taken the pulse of a nation for half a century. But today on Q he said he's saddened by what's happened to his business in the 50 years he's been behind the mic. In his new autobiography, he has some harsh criticism for today's AM hosts. (He calls Rush Limbaugh and his ilk "wackos.") What do you think makes a great interviewer? King also proudly says he's never written down a question in his life and that he prefers to go into an interview "dumb." Does he get what you want out of his guests? Who do you think is the best interviewer in broadcast history?