The Cozy Mystery List - This site has lists of cozy mystery authors and their works. (If you do not know what a cozy is, there is a definition here). There is also information on mystery TV shows and movies and on award winning mystery novels.
Dell Map Back Mysteries - A series of paperbacks, published in
the 1940's and 1950's with a map of the scene of the crime on the back cover. This article is by Gary Lovisi in Mystery Scene magazine. If you are interested in seeing a very extensive collection of Dell Map Back covers, take a look at this site.