Chairman, HarpoHost of the highest-rated talk show in television history and the country's wealthiest woman, Oprah has been called the most influential woman in the world. Her empire stretches all mediums -- film, television, books, magazine publishing and even "Oprah & Friends" on XM Satellite Radio. Her tastemaking skills now stretch even to presidential candidates and the Internet: After Barack Obama appeared on her show, Web searches for his name spiked 358 percent.
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