WILLIE NELSON
Musician on a Mission
With his BioWillie biodiesel—sold at truck stops in eight states—the redheaded stranger, 73, has brought a Birkenstock sensibility to the land of cowboy boots by targeting the biggest diesel users in the country.

LEONARDO DiCAPRIO
Best Actor
Ecolebrities—stars who champion green causes (you heard it here first)—tend to attract more than their share of criticism. They are, the argument goes, mostly naive and incapable of being meaningfully involved with anything but themselves, making them ineffective advocates for anything more serious than a Japanese energy drink. For the cynics, we have but one word: Leo. The hybrid-driving, commercial-air-flying, solar-powered DiCaprio, 32, has been using his fame to illuminate environmental causes ever since achieving the star wattage to do so. After founding the Leonardo DiCaprio Foundation in 1998 to raise awareness of sustainability issues, he chaired the Earth Day 2000 gathering in Washington, became a board member of the environmental nonprofit Global Green USA and a trustee of the Natural Resources Defense Council, and launched LeonardoDiCaprio.org to spread the conservation gospel. More recently, he co-wrote and narrated the short films Global Warning and Water Planet and signed on with Survivor producer Craig Piligian to create a reality show called E-topia, which will chronicle the green rebuilding of an entire American town.

His biggest project at the moment is a feature-length documentary that he's been working on for three years. The film, 11th Hour, which is due out later this year, chronicles the state of the planet and its ecosystems, outlining how we arrived here and what we can do to change things. "This is his passion," says co-director Leila Conners Petersen. "He's spent hours and hours in front of the camera, writing, in the edit room. He has ideas he wants to put out there, and he's doing it."

Case in point: By simply posting a question about global warming on the Web site Yahoo! Answers—"What are some simple steps or creative ideas that people can take at home and work to combat global warming?"—DiCaprio elicited more than 10,000 responses and hundreds of news stories. "Leo's job, as he's described it," says Global Green president and CEO Matt Petersen, "is to use his position to shine a light on the experts, the science, and the solutions."