World's top billionaire philanthropists

It has been a phenomenal year of giving from the world's super rich. The world's richest man and most famous philanthropist, Microsoft chairman Bill Gates, continued to tap into his enormous $32 billion (endowment) Bill and Melinda Gates Foundation to fight poverty and improve health and education around the world.

But he was upstaged in June by his good pal and bridge partner Warren Buffett, Berkshire Hathaway's chief executive, who surprised the world by announcing his decision to donate most of his fortune--$31 billion--to the Gates foundation. The pledge set the record for the biggest philanthropic contribution ever made.

Perhaps it is good old-fashioned rivalry among billionaires to see which one can outdo the others. Maybe it is peer pressure to look good among one's billionaire friends. Or it could just be a desire to leave a lasting legacy. Whatever the reason, it seems that giving generously is more fashionable than ever among the billionaires set. A $1 million gift hardly even makes headlines today.

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While it is impossible to keep track of every single billionaire's charitable pledge, in part due to some folks' preference for secrecy, we have tried to turn up as many of the big gifts of 2006 as we could. We then selected 12 of this year's most spectacular donations, which together total $35 billion.

Some of the biggest recipients of billionaire aid have been organisations helping Africa and AIDS research. The Gates Foundation's largest gift this year was $287 million, to help find a vaccine for AIDS.

One stipulation: The five labs receiving the money must work collaboratively and share all discoveries that could lead to a vaccine. In September, George Soros, the Hungarian-born financier and committed supporter of democracy around the world, said he would give $50 million over five years to help fight AIDS and poverty in Africa. Part of his donation will go toward providing HIV/AIDS treatment in 33 villages in ten sub-Saharan countries.

Sir Richard Branson, the publicity-friendly entrepreneur behind Virgin Group, has used his relationships in rural Ulusabe, South Africa, where he runs a safari lodge, to start an AIDS treatment centre.

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A noble cause, for sure, but it pales next to Branson's much more ambitious and audacious pledge, announced at President Bill Clinton's Global Initiative in September, to donate up to $3 billion of profits from Virgin's train and airline businesses to fight global warming.

Another trendy area: stem-cell research. Eli Broad, the co-founder of homebuilder KB Home, gave $25 million this year to build a stem-cell research lab at the University of Southern California's Keck School of Medicine. Other billionaires who have supported stem-cell research in some capacity (despite--or perhaps because of--the ban on federal funding of embryonic stem-cell research) include New York's Mayor Michael Bloomberg; Ray Dolby, inventor of the Dolby sound system; Intel's Andrew Grove and Oracle founder Larry Ellison.

Education and the arts still draw big bucks from billionaires. Texas oilman T Boone Pickens donated $165 million to the athletic programs of his alma mater, Oklahoma State University, but will continue to personally reinvest and manage the money.

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The former chief executive of American International Group, Hank Greenberg, gave $50 million to Yale University to help both Chinese undergrads studying at Yale and Yale undergrads studying in China. And in a nod to his childhood, energy king David Koch donated $20 million to the American Museum of Natural History in New York. Part of the funds will be used to maintain the museum's famous dinosaur displays, which Koch first visited with his father in the 1950s.