Short Stories
There are a couple of group worlds at work here. Firstly, we're great big fans of Stanlislaw Lem's "The Cyberiad", and have written some bits of fan-fiction based in his universe. I've not seen any other fan fiction based in the world of the Cyberiad, except, perhaps, for Futurama (by which I mean, not any specific episode. Just the vibe.)
So we have a couple of Cyberiad Apocryphal tales here, of which we are inordinately proud.
We also have some tales based in a Monastery. This is a group world I created for the benefit of Dave's writing block. He got excited and promised to write something for it, but it hasn't happened yet.
The premise of the Monastery is that it is a warren of cloisters belonging to different Monastic Orders, all living together on the side of a mountain. The Monastery came about in the early 1000's, when delegations of several monastic orders were sent to neutral ground in order to thrash out their differences. They put down tents and started arguing, and eventually started growing things and putting down more permanent structures, and so the Monastery grew.
As time passed, more and more Monastic Orders joined - not so much to argue the original debate, the nature of which is lost in the mists of time - but because the air there is rich with deep thought.