Al Gore
former U.S. vice president

Face it, when it comes to whipping up concern about climate change, Mr. Inconvenient Truth is the man.

Gore held the first congressional hearings on global warming in 1976 and has since won the Sierra Club's top honor, the John Muir Award (as well as an Academy Award and a Nobel Peace Prize). Now he's throwing $300 million at the We Campaign, a push for tough carbon-emission cuts.

Upside | For someone who was once labeled stiff and robotic, the guy's got star power. And he does have job experience.

Downside | "I have no plans to run." And with his trophy case filling up fast, acolytes may encourage him to hold out for sainthood.