ClueLass - Has books, groups, events, articles, FAQ, awards, research help, contests, publishers seeking writers. An excellent resource site.

Cops 'n Writers - Consulting service for mystery writers who want to incorporate police procedures and culture into their writings.

Crime Magazine - A wonderful encyclopedia of crime-related issues.

Guide to Lock Picking - Has info on types of locks, tools, how-to exercises, and even a chapter on "advanced lock picking".

HollywoodNetwork.com - Geared toward screenwriters. Many resources are only for the members but the free resources are still worth checking out.

Murder Must Advertise - A discussion list for promoting your mystery novel.

Mysterious Home Page - A nice variety of links to awards, games, magazines, newsgroups, authors, electronic texts, media, organizations, articles on themes and characters, etc.

Mysterious Writ, The - A mystery writers' group site.

Mystery Connections - Includes links to conventions, authors, mystery zines, bookstores, and interactive murder mysteries.

MysteryNet.com - Has resources such as games, upcoming mystery events, chats, etc.

Orchard Press Mystery and Writers Links - Has links to research sites, writing sites, mystery books, chats, shows, and organizations, etc.

Overbooked Book Links - An extensive list of book publishers, including small press and international publishers.

PoisonedPens - A mystery writers list.

Police Writers Association - Informs members of opportunities and news in police writing. Includes resources, networking, and up-to-date knowledge. Has a quarterly newsletter called The Police Writer.

SinC - The purpose of Sisters in Crime is "to combat discrimination against women in the mystery field, raise awareness of their contribution to the field, and promote the professional advancement of women who write mysteries."

True Crime - Has articles, tips and markets.

Twists, Slugs and Roscoes - A list of police and detective slang, especially of the 20's, 30's, 40's.

Who Done It Sites on the Web - An excellent list of mystery sites.

Zeno's Forensic Page - Has links to laboratories, employment opportunities, forums, universities, discussion lists, associations, journals. Includes resources for psychiatry, medicine, and forensic science.