The Crime Writers' Association
Smart site of the UK-based association for those with a "professional interest" in crime and punishment, with information on events, competitions, authors and highlights from the Red Herring magazine.

Forensic Science Webpage
Impressive site that covers the basics of forensic science for the lay person, with sections on investigative techniques, the (US) justice system, suggested reading and some links.

The Mysterious Home Page
Extensive bright yellow guide to mystery on the web with large collections of links on everything from etexts to conferences.

Mysteries.com
Extensive searchable database to help you find everything you need to know about your favourite mystery books and authors.

Mystery Authors
Hundreds of mystery authors listed, with reviews and ratings of their books. For each title there's a short summary, a chance to rate the book, details of awards and movie adaptations, and five similar book titles.

Mystery Online
Read a mystery novel as it is being written, or contribute sections to ongoing collaborative short mysteries at this well-laid out site.

Mystery Writers' Forum
Enormous discussion group covering every aspect of mystery writing, from "How many murders are too many?" to "Can the police ID a body just from a photo?" With a guest browsing facility and extensive links, this is a good starting point for budding mystery authors.

Sherlockian.net
Bursting with useful links, online texts and information on the Victorian sleuth and his creator Arthur Conan Doyle, this comprehensive guide provides in-depth detail on the original stories and an introduction to Victorian Britain and Doyle's writing conditions. Look out for the lighthearted links to parodies of his work and film and stage interpretations.

Tangled Web Author Directory
A stunning resource, this: dozens of crime authors classic and contemporary, with book summaries, tour news, bibliographies, biogs and reviews. There's the chance to email authors, and new/updated features are clearly signposted.

Tartcity
"Our heroines are Modesty Blaise and Emma Peel, our morals are questionable" declares the manifesto for Tart Noir, the brainchild of a group of female crime writers including Lauren Henderson and Stella Duffy. With details of book tours, original fiction, a serial story, book and film reviews, 'provocative horoscopes for the real world' - anything they feel like, really - the site is stylish, fun and committed. Looks as though it's great fun to do, too.

221b Baker Street
Site devoted to Sherlock Holmes, with pictures, links and etexts of 48 of the 60 stories.