SCOTT HARRISON, 32
Founder of charity: water, which has funded 626 water projects in 11 developing nations

FORMER OCCUPATION: Nightclub promoter

LIVES IN: New York City

HIS HEROIC TRANSFORMATION: Throwing parties for the rich and fabulous, Harrison "woke up one day and realized I was miserable." He spent two years volunteering in Africa and decided "to connect the wealth of my friends here with the extreme need there." These days he sells wells "to people who used to buy expensive bottles of vodka. Now I can get kids who are sick with waterborne diseases clean water. It's humbling."

HIS IDEA OF A GOOD TIME: "Going to villages without clean water, then raising money to help. I'm now dating someone doing the same thing I do after working together 100 hours a week."

WEB SITE: www.charitywater.org

MONTANA BUTSCH, 29
Teaches kids how to row—and succeed in school—at his nonprofit, the Chicago Training Center

FORMER OCCUPATION: Competitive college rower

LIVES IN: Chicago

HOW HE'S HEROIC: Butsch knew crew was a great sport, but also an expensive one. After attending Oxford he returned home and raised money to buy two rowing boats for use by underprivileged teens. "They got past the idea that this was a sport for elite kids pretty fast," says Butsch. "Now they wear a badge of pride." But he wanted them to have more. At his one-year-old training center, 45 kids ages 13-16 also get academic tutoring, college visits and inspirational talks with area professionals, all free: "I want this to be a platform for whatever they want to do."

WHAT HE WANTS IN A WOMAN: "She has to have a sense of humor. These kids have more self-assurance than most. When my ex visited, the boys made sly comments and formed little crushes on her. I knew it was harmless, but for someone not used to that, it could go terribly wrong."

WEB SITE: www.chicagotrainingcenter.org

Ricken Patel, 31
Cofounder of Avaaz, a nonprofit Web site that alerts its 3.3 million members worldwide to social-action opportunities

FORMER OCCUPATION Conflict resolution analyst

LIVES IN: New York City

HOW HE'S CHANGING THE WORLD: Since launching the site in '07, Patel has organized members to petition governments to prevent overfishing, to throw parties to raise awareness about global warming and, in the case of post-cyclone Burma, to donate funds to help victims. "The government was blocking aid, so we sent an e-mail alert and raised $2 million for monks there to buy people food and medicine. We're giving people the opportunity to make real change in the world. It's like idealists of the world unite."

MUST YOUR GIRLFRIEND BE SOCIALLY ACTIVE? "No. What matters to me is they have a kind heart. I enjoy being with people who are different; it's good to mix it up in a couple."

WEB SITE: www.avaaz.org