The Children's Book Council encourages literacy. This site is for writers, readers and teachers.
Horn Book offers publications about books for children and young adults.
Check Write 4 Kids for articles and tools about the art of writing children's books.
Author Vivian VanDeVelde has great information on her site for how to have a successful author appearance at your school. She also has a page of writing advice.
The Writer’s Digest website has great information for writers and contests you can participate in.
Resources for teen writers:
www.upperroom.org/devozine
I have written a lot for Devo'Zine, a publication for Christian teens. Most of the daily devotionals are written by teens themselves. You can visit their site for inspiration as well as a list of monthly topics and guidelines for submitting your own work!