I was shown the impressive materials produced by Chaosium about the fictional world of Glorantha. It is incredibly detailed not only in the history that has been created for it, but also the religious traditions of the RuneQuest realm:
These are a revival of an existing RPG mythos, but elaborating it in far greater depth and detail. I will be reading some of the items that I got from their booth and then blogging about them in more detail in the near future.