Writer's Digest Magazine
Published six times per year and on-line; tips for writers of every genre; writing prompts and exercises; contests; interviews with veteran and just-published authors; additional resources.
The Writer Magazine
Quite similar to Writer's Digest.
Daily Writing Tips
Just what it says: Each day, some new bit of writing instruction in clear, easy to digest form.
Walks writers through proper formatting
of their work and helps match them with hundreds of potential editors and publishers.