Columbia's Young Authors' Writing Contest
Bennington Young Writers Award (deadline 11/1)
Teen Ink - post your own writing, read others’ writing, and get published
Upwords Poetry - a great place for poetry ideas, and a ton of links for youth friendly publishing of any genre
Creative Writing Prompts - hundreds of writing ideas
Fanstory - contests and feedback for writers
Writing.com - online community for writers. A place to share writing and enter contests.