Ben Silbermann

A soft-spoken Iowa native, Silbermann seems like an unlikely trendsetter. But he's built one of the Valley's hottest social media upstarts. Founded in 2010, Pinterest has become a vibrant repository for some of the most interesting trends on the Internet, from cars to weddings to architecture to tattoos. It's also a virtual gold mine of data for advertisers and retailers, propelling the still-private business to a valuation of roughly $12.3 billion in June. Its 175 million monthly active users have "pinned" more than 100 billion ideas to date, yet Silbermann says the company is still "only beginning to understand" how social media impacts consumers' lives. The most overrated trend of the moment? "Expensive juice."