No.1 Mark Zuckerberg
Net worth: $4 billion
Regains his status as world's youngest self-made billionaire after falling off the list last year during the economic crisis. His social-networking site Facebook became "cash-flow positive" in 2009; recent transactions of its shares on private equity exchange SecondMarket put the site's value at upward of $15 billion. Zuckerberg started Facebook in early 2004 while a sophomore at Harvard. He dropped out after receiving funding from PayPal cofounder Peter Thiel. The number of Facebook users has surged 130% over the past 12 months to 400 million. A public offering seems inevitable, though Zuckerberg is said to be IPO-shy.
No.2 Yoshikazu Tanaka
The world's second-youngest self-made billionaire. Made his fortune from a social networking site he founded called Gree. He started out at Sony, then worked for fellow Japanese billionaire Hiroshi Mikitani at online shopping site Rakuten. Left in 2004 to set up Gree at a tech incubator. Transitioned the site into a mobile gaming-focus to compete with rivals. It's attracting around 1 million new subscribers a month, who pay for virtual clothes and accessories for online avatars that participate in social games on their mobile phones.
No.3 Sergey Brin
The Google cofounder's hot streak brings him up a couple of rankings to 24th richest in the world. His fortune grew $5.5 billion as shares of the search giant rose 70% in past year. Google revenues hit $23.7 billion. Unveiled smart phone Nexus One in January; operates with Android software. Announced upgraded version of Chrome browser in March. Emigrated from Russia, met future partner Larry Page at Stanford; duo dropped out of computer science Ph.D. program in 1998. Brin introduced goats to Google's campus last year, since animals are less harmful to the environment than lawn mowers.
N0.4 Larry Page
The surge in Google stock pushed up cofounder Page's fortune by $5.5 billion and lands him as 24th richest. Google continues to dominate search, though it has seen Microsoft's Bing search engine--launched in 2009--take a slice of its market share. The company has moved into mobile phones and mobile software with the January launch of its Nexus One smart phone, which uses its Android operating system software. Google Apps--including Google Docs and Google Calendar--are a $750 million piece of the overall business and growing. Page met Brin at Stanford, where the pair founded Google.
No.5 Robin Li
The Chinese Internet entrepreneur returns to the billionaire ranks and is now nearly twice as rich as he was in 2008 when he last made the cut. Li heads China's online search leader, Baidu, which posted a 48% rise in fourth-quarter profit. Baidu's stock rose 281% in the past 12 months, thanks to the strong results, but also more recently due to its ongoing rivalry with Google. Baidu shares, and his fortune, jumped by one-third after Google said in January it might pull out of China.
No.6 Jerry Yang
Yahoo cofounder Yang has gone through a volatile few years. The 26% rise in Yahoo's stock helped boost his fortune since last year. While chief executive of Yahoo, Yang turned down a $44.6 billion takeover bid from Microsoft, prompting activist shareholder Carl Icahn to try and oust Yang. He eventually stepped down in November 2008, replaced by spitfire Carol Bartz. Yahoo formed a search partnership with Microsoft in July 2009, in which Yahoo will run ad sales for Microsoft's Bing search engine. The company turned 15 in February 2010.
No.7 Pierre Omidyar
Omidyar's fortune is up $1.6 billion thanks to a surge in eBay's stock price: shares rose 115% in the last year. EBay's 2009 sales were $8.7 billion; the Web site had 84 million users. The company completed a 70% sale of Internet calling unit Skype in November 2009, valuing Skype at $2.75 billion. A French-born computer programmer, Omidyar launched online auction outfit eBay in 1995. He remains chairman. Has pledged more than $900 million to nonprofit causes and for-profit investments, and supports issues ranging from microfinance to his home state of Hawaii.
No.8 Peter Thiel
Thiel returns to the billionaires list thanks in part to the rising valuation of Facebook, a company in which he initially invested $500,000 back in 2004 as the first outside investor. A chess prodigy, he was ranked seventh in the U.S. under-13 bracket by age 12. As a Stanford law grad student, Thiel spent time at Credit Suisse before founding Thiel Capital in 1996. Renamed Clarium Capital in 2002, the fund reportedly fell 25% last year. Thiel also cofounded PayPal in 1998, and sold the company to eBay in 2002 for $1.5 billion. He netted $60 million. He plowed those proceeds into venture capital outfit Founders Fund in 2005.
No.9 Michael Dell
Dell's net worth rose $1.2 billion from a year ago, but his ranking among dropped to 37th from 25th last year. The leader of one of the world's largest PC-makers, trying to claw its way back to the top, completed a purchase of IT services outfit Perot Systems in November 2009. Dell returned to the company helm two years ago, brought new management, restructured divisions. Dell introduced smart phone and tablet devices in the past few months. The company's stock slipped nearly 10% in the past six months, however, and revenue fell 13% in the year ended January 2010.
No.10 Jeffrey Skoll
Age: 45Also helped by eBay's rising stock is Skoll, eBay's first president and full-time employee. Skoll, no longer involved with the company, now focuses on inspiring social action by launching entrepreneurs through his Skoll Foundation producing movies through Participant Media. He backed the Oscar-winning film, An Inconvenient Truth, the global-warming documentary that featured former Vice President Al Gore. Skoll pumped gas in Toronto before getting an M.B.A. from Stanford in 1995. He received the Producers Guild of America's Visionary Award in January 2010.