Ben Silbermann

The CEO of the fastest-growing website in Internet history may not be a coding genius, but 19 million visit his image-sharing site every month. Silbermann is a collector with a strong design sense. But the Des Moines native knows what he likes, and it happens to be liked by a lot of other people too: It regularly beats out Twitter and Facebook in driving traffic to smaller websites. And its growth shows no sign of slowing. Pinterest added apps for the iPhone, iPad, and Android this summer, and switched to an open-registration process. (Previously users had to be invited to join.) In September, Silbermann took on a role even bigger than running a company valued at $1.5 billion. He became a father. Collect this: Silbermann never lost his childhood love for stamp collecting (but he did give up on insects and rocks). –Ryan Bradley