When the Dave Matthews Band realized it had produced 18,000 tons of carbon dioxide in 15 years of touring, it turned to NativeEnergy to ease its guilt. NativeEnergy finances new clean-energy projects on Native American reservations, with money from individuals and businesses looking to offset the carbon emissions they produce. Drive an SUV? Ninety-six dollars a year should cover it. Investors have included Al Gore, the Clinton Global Initiative, even the NFL. They've found financing for new wind farms, solar generators, farm methane facilities, and a wastewater-treatment plant--and steered tribes to new revenues that don't involve slot machines.