I just stumbled across a list of the 40 of the Best Websites for Young Writers. They have a ton of great resources listed, including links to the Young Writer's Society, Eighteen Questions, Writing Contests, and a whole armful of grammar sites that can help you decide which "lay" to use.
However, don't forget that your friendly neighborhood library offers tutoring help through Brain Fuse (click the box in the upper right corner!). They can give "feedback on your writing from an expert tutor in our writing lab or... email you helpful comments regarding your homework question." Yep, you can send them your papers for critique - or chat live with a tutor. Pretty awesome.