Although this site heavily promotes a book (Fear of Writing), it has some useful parts. This site includes writing prompts, examples written from the prompts, and information about starting a writing circle.
Writer's Digest.com home page presents you a new prompt each week. This is page for people who love to write with an eye on publishing their work. This promotes the magazine Writer's Digest There is a very active writer's community here. Also it has numerous writing contests.contests
This would be a good place to look for writing prompts. Creative Commons Licensed. See the FAQ page for questions. He allows and encourage teachers to use this stuff. This site is a one man operation and stories aren;t posted immediately. He does not approve of every story.
This is a site dedicated to the practice of using writing as a means for self improvement. There s a page of photographs that can be used as visual writing prompts.
Sponsored by the Northern Nevada Writing Project, "WritingFix believes this: No one writes with just the right-side of his/her brain. The brain is too complex and cross-wired to believe that. But we believe this too: Ideas that spark a writer's inspiration can start on the right-side of the brain. And for that reason, all writing activities categorized on this page celebrate a right-brained approach to beginning a piece of writing. This page celebrates approaches that are serendipitous. This page celebrates approaches that are random. Devote part of your journal or your writer's notebook to right-brained sparks."