Some of my favorite speculative fiction websites, listed in no particular order:
1. Ralan’s Webstravaganza: A fairly extensive listing of markets, paying and non-paying for horror, sci-fi, fantasy, etc.
2. Duotrope’s Digest: Another markets database; this one is sortable and includes non-genre markets as well. Also offers statistics about the markets, such as the acceptance rates, etc.
3. Endicott Studio: If I had to pick a favorite website, this would probably be it. A treasure trove of mythology, folklore, and fairy tales, and information for writers who love them.
4. Writing Science Fiction & Fantasy: Jeffrey Carver’s free online writing course. If you’re an accomplished writer, a lot of this is probably repetition, but some of it probably isn’t, and a refresher never hurt anyone. If you’re just beginning, this site is invaluable.
5. Vision: A Resource for Writers: An online zine dedicated to writers, with all sorts of useful info.
6. Uncle Orson’s Writing Class: Part of Orson Scott Card’s Hatrack River website. Tips, hints and info from one of the masters.
7. Pitfalls of Writing Science Fiction & Fantasy: Vonda N. McIntyre’s advice to writers.
8. David Walton’s Writing Page: A plethora of advice to spec-fic writers.
9. Critters Workshop: One of the best writers’ workshops online, and the site includes a number of resources, including market stats.
10. SFWA’s Articles on Writing: Advice from a number of pros.
This is, of course, far from an extensive list. If you have any resources you’d like to share, please post them in the comments!