There's this little thing they do on rpg.net called "craft a setting". The general of it is as follows the person titles the setting concept to give it a broad overview(Tropical fantasy, Golden age of the Lizard King, etc) then each person posts a setting detail, building up a complex little universe via multiple people. Generally the only rule is not to openly contradict previous posters. Sometimes the post are IC discussions of a part of the universe a snapshot if you will.
With that out of the way, I was wondering where to put such an endevour on site, it could easily be a Game, a Universe, a RP, or even captioned.