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Many of America's ultra-rich continued to give big donations to charity in 2008, despite the worst financial crisis in decades. In the past year, seven philanthropists gave north of $200 million and nine gave more than $100 million to causes ranging from wilderness preservation to fighting malaria. Warren Buffett and Bill Gates remain far and away the biggest givers overall, but two of 12 newcomers to the list pledged to give more than $1 billion away: William Barron Hilton, co-chairman of the Hilton hotel chain who pledged late last year to give away 97% of his wealth—some $1.7 billion—to his family’s humanitarian foundation and Peter G. Peterson, co-founder of the investment firm Blackstone Group, who gave $1 billion this year to establish a foundation that promotes fiscal responsibility. Read their stories—and those of the 48 other philanthropists on BusinessWeek's list—here.