1.Prince Albert von Thurn und Taxis
Net worth: $2.1 billion Age: 25
First appeared on our World's Billionaires list at age 8, but officially inherited his fortune in June 2001 on his 18th birthday. Attended high school in Rome, studied economics and theology at Edinburgh University in Scotland. Assets include real estate, art, a technology company and 30,000 hectares of woodland in Germany. This eligible bachelor tours with a German auto-racing league.
2.Sergey Brin
Net worth: $12 billion Age: 35
Google co-founder continues to dominate search business despite facing strong headwinds. Company's stock is down 30% in the past 12 months, slicing $6.7 billion from personal balance sheet. Posted better than expected earnings in January; trimmed staff and employee perks. Professor's son emigrated from Russia, met partner Larry Page in a computer science Ph.D. program at Stanford University. Duo dropped out in 1998 to start Google from a friend's garage. Sales: $21.8 billion. Net margins: 19%.
3.John Arnold
Net Worth: $2.7 billion Age: 35
The youngest billionaire in America keeps getting richer. Wunderkind's Centaurs Energy hedge fund said to be up 80% in 2008. Energy trader diversifying into hard assets: power plants, storage facilities. Father was a lawyer, mother an accountant. Raised in Dallas, graduated in three years from Vanderbilt University. Became an oil trader at Enron in 1995; said to have generated $750 million of the firm's profits in 2001. Founded Centaurs after Enron's bankruptcy. Returns said to exceed 200% a year since 2002.
4.Larry Page
Net Worth: $12 billion Age: 36
Professor's son, heads Google's product division. Met partner Sergey Brin in a computer science Ph.D. program at Stanford University. Duo dropped out in 1998 to start Google from a friend's garage. Initial financing came from angel investors I. Ram Shriram, Andy von Bechtolsheim, professor David Cheriton. Venture capital firms Kleiner Perkins Caufield & Byers and Sequoia Capital pitched in $25 million; everyone made billions when Google went public in 2004. Fortune down $6.6 billion since last March after stock fell 30%.
5.Andrei Melnichenko
Net worth: $1 billion Age: 37
Young industrialist's fortune fell more than 80% since last year as energy and fertilizer prices plummeted. The son of a respected Soviet physicist studied physics at Moscow State University. Dropped out in 1993; founded MDM Bank. Teamed up with Sergei Popov, accumulated industrial empire: coal, fertilizer, energy. Married to Yugoslavian model and pop princess Aleksandra Nikola. Reportedly spent $2 million in 2007 for Jennifer Lopez to perform at his wife's 30th birthday party. Couple's Web site lists favorite music, travel destinations and bios of Andrei, Aleksandra and their prized pup, Vale.
6.William Ding
Net Worth: $1.1 billion Age: 38
Founder of China's No. 2 online game company, Net ease. Was once China's richest man. Flagship game, "Fantasy Westward Journey," among nation's top 10 downloads. Signed three-year contract with U.S. game developer Blizzard Entertainment to distribute "StarCraft II" and Battle.net to Chinese mainland. Netease's U.S.-listed shares up 9% in past year. Enjoyed double-digit profit growth.
7.Sheik Mansour Bin Zayed Al Nahayan
Net Worth: $4.9 billion Age: 39
Investor with hoards of cash is a member of Abu Dhabi's royal family. Last September, he shelled out $300 million for soccer team Manchester City. One month later, he rescued British bank Barclays from possible nationalization with a controversial $5 billion cash investment. Wields major clout at home: chairs the state's oil-oriented sovereign wealth fund; serves as minister of United Arab Emirates Presidential Affairs. Avid sportsman--enjoys soccer and endurance riding.
8.Chu Lam Yiu
Net Worth: $1.5 billion Age: 39
Chairs Huabao International, which makes fragrances and flavorings for use in cigarettes, detergents, beverages, dairy products and cosmetics. Fortune fell 20% since last March after manufacturing slowdown. Founded the company a decade ago; took it public through a backdoor listing. Sold 9% in 2008; still owns two-thirds of shares. Holds several leadership positions in local industry groups.
9.Jerry Yang
Net Worth: $1.1 billion Age: 40
Embattled Yahoo! co-founder quit as chief executive in January. Settled proxy contest with shareholder activist Carl Icahn for control of company. Icahn won three board seats. Yahoo! stock is down nearly 55% since original Microsoft offer last February. Met partner David Filo in grad school at Stanford, turned Internet directory project into Web portal Yahoo!. Took it public 1996. Agreed to ad partnership with Google last June following Microsoft debacle; deal to deliver Google ads alongside Yahoo!'s search results fell through months later
10.Kenneth Griffin
Net Worth: $1.5 billion Age: 40
Founder of Chicago hedge fund outfit Citadel reeling from steep losses: Flagship Wellington Fund plunged 55% in 2008. Shut down Fusion, a $1 billion hedge fund of funds, in October. Net worth down $2.2 billion--60%--since September. Started trading stocks from Harvard dorm room; founded Citadel with $4.6 million in 1990. Today, firm manages $13 billion (down 35% from peak last year); accounts for roughly 10% of U.S. equity trading volume. One of five billionaire hedge fund managers to go before congressional panel last November. Bought Jasper Johns painting "False Start" for $80 million in 2006.
Estimated Income : $9.7 million 
