Below is a list of my personal favorite *free* websites for writers, at any level. I'll update as I come across them. I have used or checked out in detail every single one of the below.
Absolute Write - an interactive forum of thousands of writers of all genres from all over the world, where you can chat, post queries/pages for critique, and ask agents and editors questions.
Romance Divas - an interactive forum dedicated solely to the genre of romance, where you can post pages/queries for critiques, ask questions, chat, rant, and gush with fellow romance lovers.
Critique Circle - purely a critique site for your work, the quality here is fairly good. You can post stories, queries, chapters, etc and get some great feedback. For the lowdown on how to get started, see the information page.
Writer Beware - from the website: "Shining a bright light into the dark corners of the shadow-world of literary scams, schemes, and pitfalls." Blogs about things to be aware of as a writer!
Querytracker.net - a great site to help you build your submission list, and check stats for agents you want to submit to! Just be sure to LOOK AT SUBMISSION GUIDELINES before you send as these listings tend to be a little outdated.
Below is a list of non-free but still extremely valuable websites and organizations for authors:
Author's Guild - From the website: Members of the Authors Guild receive free book contract reviews from experienced legal staff, discounted health insurance rates in some states, low-cost website services including website-building, e-mail, and domain name registration, access to our free Back in Print service, our quarterly print Bulletin, and invitations to panels and programs throughout the year.
SCBWI - The best organization to be a part of if you're a children's author or illustrator. Puts out monthly newsletters and a magazine chalk-full of advise, has conferences, and critique and chapters in YOUR area you can meet with once a week. It is, as they say, a network for the exchange of knowledge for writers in the children's field.
RWA - Similar to the above, this is the best organization to join for writers of romance. Also includes newsletters, conferences, chapters and contests (judged by editors and agents); a networking and learning must for the romance writer.
Heck, let me just list out a bunch of these fabulous networks to join: Historical Writers' Association, Mystery Writers of America, Science Fiction and Fantasy Writers of America
Helpful blog posts:
How to Revise your Manuscript
Query Template and Awesome Query Tips (fiction & non-fiction)
Quick Grammar Review
Ingredients for a Non-fiction Book Proposal
Peripheral Character Development
Common Manuscript Mistakes and Market Terms
Cheater's Guide to Requested Materials
DON'T GIVE UP (an inspirational post)
Want to support the PRINT side of publishing?! Sure you do. Check out these books:
Guide to Book Publisheres, Editors, and Literary Agents (released annually) by Jeff Herman
The Elements of Style by Strunk and White
And READ READ READ in the genre you want to write!!!