Some people here may have heard of the SCP Foundation, some probably haven't.  For those who aren't already aware of it, the SCP Foundation is a huge collaborative writing project about a fictional organization of the same name that protects the world from anomalous things.  A word of warning before you click on the link: like most things with a lot of contributors from all over the internet, the entries in the SCP wiki range in tone from benignly funny, to genuinely scary, to (occasionally) downright disturbing and horrific.  To be clear, although the quality of the writing is very high, the SCP fandom originally got started on 4chan.  Your work web filter will probably block it, although there are not (to my limited knowledge) any explicit images on the site.  You have been warned.

Here's the link:  http://www.scp-wiki.net

Lest I give the wrong impression, the vast majority of the wiki is fairly safe if you don't mind Slenderman-esque horror stories.

The reason I'm bringing this up is that I recently discovered that the entire wiki is available under a FOSS-compatible license, namely CC-BY-SA 3.0.  It also is something of a holy grail for me, as for quite a while now I've been looking for a well-developed fictional world with an existing fanbase that people are actually allowed (and even encouraged) to build on and share in a way that is compatible with libre software.

If this gives anyone any game or art ideas, I'd be happy to have people post and discuss them here, provided that everyone use good sense as far as determining what is reasonably appropriate (and if you're not sure about something, feel free to ask me first), and that you comply with their license.

P.S. If this is the first you've heard of the SCP foundation and you're curious enough to click the link, don't read it at night if you plan on getting any sleep.