CEO, Amazon.comRank: 12Why he matters: Bezos has run a wildly successful Web company for more than a decade, but he's not resting on his laurels: Having built the world's largest online bookstore, he's now trying to become the largest provider of back-end support and services for fledgling Internet companies.
Amazon's Simple Storage Service seems far removed from its core retail business, but Web 2.0 companies have embraced the pay-as-you-go product as an alternative to building their own server farms. Nevertheless, analysts worry that despite the company's pioneering roots and massive technology infrastructure, it lags behind competitors like Google and Yahoo. But don't count the Web's old man out just yet; Amazon's first-quarter profit of $111 million was up 118 percent from last year.
Meet 50 Who Matter winner Gina Bianchini. Her site, Ning, lets anyone be a social networking mogul. (more) 
