Age: 26
Occupation: CEO, Mashable
As a 19-year-old living with his parents in his native Scotland, Cashmore became obsessed with sites like Facebook and figured, Why not me too? He promptly dropped out of school and started the innovative news site Mashable, the Internet's go-to source for coverage of the social-media business. Now 26, he's also the square-jawed face of the industry; under his handsome profile, @mashable has a Twitter following of nearly 3 million people.