Economist Steven Levitt has won the prestigious John Bates Clark medal in economics. Levitt's most famous co-written paper is The impact of legalised abortion on crime:

We offer evidence that legalized abortion has contributed significantly to recent crime reductions. Crime began to fall roughly 18 years after abortion legalization. The 5 states that allowed abortion in 1970 experienced declines earlier than the rest of the nation, which legalized in 1973 with Roe v. Wade. States with high abortion rates in the 1970s and 1980s experienced greater crime reductions in the 1990s. In high abortion states, only arrests of those born after abortion legalization fall relative to low abortion states. Legalized abortion appears to account for as much as 50 percent of the recent drop in crime.

Another one of his greatest hits is An economic analysis of a drug selling gang's finances

Update from Razib: Also check the dialogue between Levitt & Steve Sailer in Slate a few years back.