Bureau of Justice Statistics http://www.ojp.usdoj.gov/bjs/
FBI Publications and Reports http://www.fbi.gov/publications.htm
A wide range of reports on the FBI, terrorism, white collar crime, cyber issues, and violent crime.
Uniform Crime Reports http://www.fbi.gov/ucr/ucr.htm
The program was established in 1929 at the urging of police organizations who needed "reliable, uniform crime statistics" on a national level. Since 1930, the FBI has provided this information.
Sourcebook of Criminal Justice Statistics http://www.albany.edu/sourcebook/
Data from more than 100 sources about many aspects of criminal justice in the United States. Sections focus on Criminal justice characteristics, public opinion, crime, victims, arrests and seizures, court, prosecution and sentencing, parole, jails, prisons and the death penalty.
National Criminal Justice Reference Service http://www.ncjrs.gov/viewall.html
Wide array of statistics arranged by topic.
Crime-Social Statistics Briefing Room http://www.whitehouse.gov/fsbr/crime.html
Highlights of major crime statistics - homicide, violent crime, drug arrests, correctional population data.