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79 million: Monthly audience for The Huffington Post, per comScore

Why she matters: The mogul's reach continues to extend with March's New York Times No. 1 best-seller Thrive: The Third Metric to Redefining Success and Creating a Life of Well-Being, Wisdom, and Wonder and her AOL-owned website expanding to its 10th country, Brazil. HuffPo's global audience has increased by 12 percent during the past year.

Big get: The WorldPost, a joint venture with billionaire financier Nicolas Berggruen, shows off the New Yorker's world-class Rolodex with a slate of contributors including Bill Gates, Richard Branson and Yo-Yo Ma. Its board is equally impressive, boasting Google's Eric Schmidt and eBay founder Pierre Omidyar.

Proudest accomplishment this year: It's a tie between the launch of WorldPost in January and Thrive, which Huffington, 63, calls "a deeply personal book" inspired by her mother. Of the book's theme, the mother of Yale students Isabella and Christina (the latter made waves in Glamour's September issue, penning an essay detailing her recovery from drug addiction) says, "Our traditional notion of success based solely on money and power is dangerous and costly -- and is not making anyone very happy."

Nemesis: None, except an inner voice she describes as "the obnoxious roommate" living in her head. "It feeds on putting us down and exploiting and magnifying our insecurities and doubts," she says.