Creative Conclave: A collaborative effort to create an original fantasy world for use in role-playing games and writing.
Fantasy World Builders Forum: Fantasy world builders discussion about deities, races, geography, curious characters, classes, and locations.
Yahoo! Groups: rpg-tools: Mailing list and group to share information about tools useful to people creating imaginary worlds and using them for storytelling, writing, roleplaying or wargaming.
Yahoo! Groups: world-create: Forum for world creation and development.