GumGum's Ophir Tanz Spins Gold from Ads on Images Online This twentysomething innovator created a successful digital ad network for Web images. Learn how he did it. Part of our annual Young Millionaires report.

When he was 13, Ophir Tanz decided he'd never be able to work for anyone else. By 15, he had started his first company, an interactive branding agency called Fluidesign, which he sold before heading off to college. After graduating from Carnegie Mellon in 2004 with both bachelor's and master's degrees, a brief 10-month stint at the Bridgewater Associates hedge fund confirmed what he had long known: "It was a great salary, I learned a lot, but I just couldn't help myself," he says of his entrepreneurial leanings.

Now 29, Tanz runs Santa Monica, Calif.-based GumGum, a digital network that places targeted advertisements over pictures online. "Basically, we pioneered a way for publishers to make money through ads on images," he says.

GumGum claims to reach 110 million unique visitors per month and says its smoothly integrated, in-image ads are clicked on as much as 20 times more than traditional online spots. This has enticed premium publishers like Gannett, Time Warner, TMZ and Hearst to sign on with the network, which hosts big-name advertisers such as Sony, Jack in the Box and Curves.