Writing Sites
There are literally thousands of "writing sites" out on the web. Here are a few that I find useful:
Fiction Factor: Has a free news letter, and depth of varied articles on writing and writing related topics. I've contributed a number of articles there. It also has sister sites which can be reached through the main site. They focus on different genres.
SFWA (Science Fiction & Fantasy Writers of America): Articles and information for writers, mainly of fantasy and SF.
Preditors & Editors: A great site with articles and listings, including recommendations and warnings about publishers, agents, etc.
Short Mystery Fiction Society: A site with some links to markets and information about (you guessed it) short mystery fiction.
Ralan's Webstravaganza: One of the most extensive and up-to-date listing of fiction markets (mainly but not exclusively SF, Fantasy and Horror).
Fiction Addiction: An active site that has some useful articles and information for writers. I am not keen on the posting of stories and articles for review there, as posting there may use up 'first electronic rights' in the eyes of some publications.