264. Scott Cook
$3 billion self-made score: * source: software age: 65 residence: Woodside, calif. m.b.a., harvard ’76 In 1983, Cook cofounded tax and personal finance software firm Intuit. Today 42 million customers use its products, including Quickbooks and Turbotax. He is chairman of Intuit’s executive committee and sits on Procter & Gamble’s board.