A wiki would be neat - I've seen them used to great effect before. We would need people who know how to make and maintain them, though - I know I don't have those skills, but perhaps some of us do.

That would allow people to put up what they know, and add things when they invent something new. Also, once we can get a good guide on how to do things, we can start being fancy and citing the threads where the information shows up - someone who updates the Wiki with a new town in Salvar would cite the thread where that town was used, allowing people who are interested in using that place to see what was there when it was last visited.