He's gone from MTV to MP3, and now he's leading a grassroots rebellion called podcasting. Why amateurs may soon rule the airwaves (begin download now).

Nick Machalaba/Penske Media via Getty; Evan Agostini/Getty. Among MTV's "fab five," J.J. Jackson brought the most experience to his VJ role, starting first in the late-1960s at WBCN-FM in Boston ...