Meet 30 Cool Young Entrepreneurs

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15 of 30

Sean Whalen

Whalen, 28, developed the AlterG anti-gravity treadmill with his father, a former NASA research scientist. The machine, which allows users to walk or run at just 20 percent of their actual body weight, is ideal for sports-injury rehab. U.S. soccer star Oguchi Onyewu, who used the treadmill to get healthy for the 2010 World Cup in South Africa, is a spokesperson for the company. Whalen projects $10 million in sales this year. Read more.