Ooh, research links!
http://www.atf.gov/statistics/index.html - ATF Firearms trace data and US manufacturing data.
http://www.cdc.gov/injury/wisqars/index.html - US CDC Wisqars death and injury statistics query tool
http://www.bjs.gov/ - US Bureau of Justice Statistics - Corrections, Courts, Crimes, including the
National Crime Victimization Survey
https://www.ncjrs.gov/ National Criminal Justice Reference Service; this is the vehicle through which a lot of US Gov't funded research gets published
http://www.albany.edu/sourcebook/ - University of Albany's Sourcebook of Criminal Justice Statistics
http://www.ojjdp.gov/ojstatbb/ezashr/ - a specialized Easy Access to FBI Supplemental Homicide reports (since homicide stats seem to be interesting to many people)
http://www.ussc.gov/ United States Sentencing Commission (Fixed - thx, Mr McGee!)