Bureau of Justice Statistics
The BJS provides a wealth of crime and criminal justice data compiled by the U.S. government and links to available data on other government websites.
National Archive of Criminal Justice Data (NACJD)
The NACJD at the ICPSR contains a wealth of data relevant for scholars interested in crime/criminology. The data cover topics such as offical crime statistics (at the national and state levels), surveys on attitudes towards crime, surveys of crime victims, and the criminal justice system.