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Celebrities -- they're more than superior human beings, they're money-making machines. If these celebrities were stocks, which would be the shrewd buy?

One sure sign of celebrity is first-name recognition, and today's contestants have certainly reached that pinnacle. Oprah and Martha are brands known worldwide, Oprah for compassion and wisdom, Martha for style and elegance.

Martha Stewart's brand is still tainted by her 2004 insider trading conviction and her stretch in Camp Cupcake. Before then, her growth from model and stockbroker to America's favorite lifestyle celebrity was impressive. After authoring the bestselling book Entertaining in 1979, she transitioned to television with her hit show Martha Stewart Living, for which she gathered several Emmys. In 1987, she inked a lucrative deal with déclassé retailer Kmart as a lifestyle consultant, to help it break into higher price-point retailing. In 1990, with Time Warner (NYSE:TWX) she launched Martha Stewart Living Magazine. The zenith of her career came in 1997 when she took herself public. The IPO for Martha Stewart Living Omnimedia (NYSE: MSO) made her a billionaire.