For both published and amateur writers, but it's much bigger than some of the others I've listed. The stories are categorized by genre as opposed to just fiction and nonfiction. The site includes a forum, chatroom, and an online form to submit your work. Also, they are much less restrictive as to the content they will allow. I think this is definitely one I'll try having my own stories posted on.

And here's another one for unpublished writers to send their works to. I'm so jealous. I tried to have a site like that once, and it didn't work out very well. Nobody ever sent me anything to post.

*sniffles*