The Association of Writers & Writing Programs (http://www.awpwriter.org) - Information about writing programs and centers, conferences and contests. Produces the journal The Writer's Chronicle.
Internet Public Library: Creative Writing Has a good collection of links to useful sites covering many aspects of creative writing
Science Fiction and Fantasy Writers of America SFWA is a professional organization for authors of science fiction, fantasy and related genres.
There are countless Web sites devoted to publishing and advising writers. A few useful ones are:
Poets and Writers The online content of the essential print magazine.
Poetry & Literary Magazines, Journals, Ezines - 2005 A clearinghouse of links to more than 400 literary journals, many of which maintain submission guidelines on their sites.