The paper reviews the recent evolution of leniency programs for cartels in the US and EU, surveys their theoretical economic analyses, and discusses the empirical and experimental evidence available, also looking briefly at related experiences of rewarding whistleblowers in other fields of law enforcement. It concludes with a list of desiderata for leniency and whistleblower reward programs, simple suggestions how to improve current ones, and an agenda for future research. The issues discussed appear relevant to the fight of other forms of multiagent organized crime - like auditor-manager collusion, financial fraud, or corruption - that share with cartels the crucial features that well designed leniency and whistleblower programs exploit.