You can argue whether imitation really is the sincerest form of flattery. But what is certain is that when imitation takes the form of celebrity impersonation -- and it resonates with a mass-media audience -- the person being imitated has been stamped as a cultural icon.

And so it is with John Madden, who announced his retirment from broadcasting today.

Comedian Frank Caliendo built a career using his Madden impersonation as a launch pad by mimicking Madden's overwrought delivery. The broadcaster is famous for hawking products from hardware to foot powder and in this skit, Caliendo lampoons Madden-the-pitchman.