No issue cuts across social and economic lines like corruption. Payoffs, conflicts-of-interest, and corrupt practices contribute not only to an unfair playing field but also to poor development, environmental destruction, and organized crime. In its various forms, corruption is perhaps the number one issue faced by journalists. Here are four leading journalists who have investigated extensively on the topic. They'll talk about what techniques they use to follow the money, develop sources, and publish stories that corrupt officials thought would never appear.