4. Mark Zuckerberg, Facebook
Age: 29
Last year's Ranking: 4Stage of global conquest: A year after the IPO fiasco, all is well again at Facebook. Although Facebook stock is now finally a few dollars above its IPO price and may climb further, this won't change the problem that ordinary investors missed out on the spectacular growth in the company before it went public.
In its most recent quarter, Facebook reported mobile-ad revenue of $656 million, up from roughly zero a year earlier. Advertisers are expected to spend $6 billion on the site in 2013.