Lime GroupMark Gorton made his name with LimeWire, the popular - and controversial - file-sharing application. He runs three other businesses under the Lime brand: a $100 million - plus quantitative hedge fund, a medical software operation, and Lime Brokerage, which is gaining a reputation as one of the fastest trading systems on Wall Street. But the project dearest to Gorton is his nonprofit, The Open Planning Project (TOPP), a grass-roots effort to reduce the number of cars in America's cities. Gorton, who bikes to work, sees TOPP as a model for open-source government. --O.R.