Centre for Crime and Justice Studies (CCJS)
Charity which aims to inform and educate about all aspects of crime and the criminal justice system. Houses a wealth of UK criminal justice links, events, and publications, including The British Journal of Criminology and CJM.
http://www.kcl.ac.uk/depsta/rel/ccjs/

Crime Spider
Search engine that crawls the web for law enforcement and crime related sites.
http://www.crimespider.com

Crimenet
Australian based service provides a database of convicted criminals, con artists, frauds, scams, paedophiles, sex offenders, stolen property, missing persons, and unsolved crime.
http://www.crimenet.com.au

Smoking Gun
Large collection of public documents on crimes, celebrities, politicians, and the FBI.
http://www.thesmokinggun.com

TheCrimePortal.com
Web directory includes news, prevention, statistics, law, famous crimes, forensics, corrections, and victims' sites.
http://www.theCrimePortal.com