MICHAEL DELL, 42
Cofounder, Michael & Susan Dell Foundation
Grandiose global aid initiatives are noble goals, but Michael Dell prefers to apply the basic rule that helped make him a billionaire in the computer business—you don’t invest in a new project until you’ve tested a prototype. Since cofounding the Michael & Susan Dell Foundation in 1999, he has shelled out more than $115 million to nonprofits in his native Texas, with the idea that these pilot efforts can be tested, perfected, and then exported. “Many of the initiatives in Central Texas have been models for success in other communities,” he says. “Our foundation’s scope has grown across the U.S.” And beyond. With a $1 billion endowment, the foundation is funding programs, such as teacher-development projects in Central Texas and now in Central India, that show local testing can yield global results.

MELINDA GATES, 43
Bill & Melinda Gates Foundation, Co-chair
When, in 1999, Bill and Melinda Gates were investigating causes to contribute to, they discovered that malaria—a disease that kills more than a million people a year, most children in Africa—had largely been overlooked by U.S. philanthropists. Melinda told Time magazine they had found a “vacuum that does need to be stepped into.” In 2005, the Bill & Melinda Gates Foundation, which effectively doubled in size in 2006 when Warren Buffett made a donation of $31 billion, provided more than $500 million to help develop affordable vaccines and drugs to treat the disease as well as prevention programs. Since then, corporations such as Exxon Mobil, Pepsi, Chevron, JP Morgan, and KPMG have joined the Foundation’s fight to eradicate malaria; the Bush administration even hosted a summit of political leaders, scientists, and advocates. “When you’re the largest philanthropic organization on the face of the earth and your resources come from people who’ve made good bets in the past, people tend to follow your judgment,” says Helene Gayle, president of CARE, a group that fights global poverty. “Melinda has an ability to connect with people from all walks of life. People enjoy working with her.”

BEN GOLDHIRSH, 27
GOOD media, Founder; Goldhirsh Foundation, Director
His father championed entrepreneurs by founding Inc. magazine in 1979, but Ben Goldhirsh is applying the same start-up spirit—and a hefty chunk of his inheritance—to a much different business: philanthropy. Along with his sister, the Brown graduate runs the Goldhirsh Foundation, which donates millions annually to cancer research and public-education programs that teach entrepreneurial skills to kids. Goldhirsh also founded the three-year-old GOOD media empire, which includes Good magazine, a publication promoting social consciousness (all subscription fees go to charity—one of the subscriber’s choosing) and Reason Pictures, whose films explore everything from global drug trafficking to immigration politics. “We’re celebrating the sensibility of giving a damn,” says Goldhirsh. “That’s got to become the dominant sensibility, because there really isn’t any other choice.”