The Bohemia Saga is a combination of freeform collaborative storytelling and guided, campaign driven, group story arcs.
Aolyth is a storytelling community for the PC game Neverwinter Nights. It is a dark fantasy world drawing heavily from gaelic and Arthurian influences.
Pure Storytelling for Role-Players, Pure Role-Playing for Story Tellers. A writing sanctuary where you can create your own world and share it with like minded individuals.