Adam Corolla, formerly of The Man Show and Loveline, now churns out one of the best, funniest, podcasts in the world. Every episode is downloaded by millions of people all over the world, and he's set the bar for what the format can do. Recently, he tried to get his friend and Loveline co-host Dr. Drew Pinsky to call in to the show and discuss pneumonia.
It didn't happen, because Pinsky was afraid his career would be damaged if he picked up the phone.