If anybody's still on here (lol), I had an idea.
Quite a few of us have compared Avatar to Star Wars, I not being an exception. Star Wars's expanded universe is among the most vast, diverse, and capacious as they get. (Although, lol, only about 1/4 of it is good)
Avatar has too esoteric an audience to get this treatment, although our optimists believe the movie will change this. Despite this, what if WE were to make the EU. Short stories, novellas, etc. We could make a shared fanfiction.net account in which we'll post new chapters/episodes of our tales. We can cover anything from various minor characters in the Avatar universe to events 300 years in the future. The amount of stories we can tell is nearly boundless.
If you want to sign up, request a STORY, etc., go to MAH BLOG.