I've used MediaWiki for that, albeit we used a freebie discussion board for conversing and storytelling. Okay, and I built a custom website too, but that came first - before we put up the wiki.
Main site for the world of Aurora
from which you get to the Aurora wiki.
Really, we could have made do with just the wiki, I bet. That world is in stasis now - active play fizzled out a while ago. That's happened before, and after some inactivity, a nucleus of interested folks would get some development and storytelling going again. If you're doing a cooperative venture, you want to ensure it can go on without any one person, even yourself. Long ago the original leader of Aurora left, assumed nobody wanted to continue, and deleted the web presence.... ThAt was a bit hard to recover from :-/. What you see now has been in place since maybe 2006. Umm - expect some broken links - players would host some info on their own websites, and some have dropped into oblivion.

The invision board was good for interaction among players. Nowadays I'd probably set up a bulletin board or blog on my own host, like I host the wiki. Many ISPs offer pretty much pushbutton creation of wikis, blogs, boards, what-have-you. We added a couple of extensions to mediawiki - 'confirm user accounts' and 'user merge and delete', and a few others that added interesting capability. It took configuring pretty tight user account permissions before we quit getting spam signups and posts - only logged-in approved users can edit at all. I totally understand why CG had to drop a wiki part - they're hard to run wide open yet safe from vandalism. ISPs fix it so updates to the eay-install apps are also easy.

As if that wasn't enough of a project, there was an even earlier geofiction world I helped with, Scandia. You'll see maps from both Scandia and Aurora in my CG albums. Both planets have been intentionally rebooted at least once - Scandia keeping the same base geography, and Aurora starting over with a wholly new map. (Fractal Terrains, YEAH!) I joined Scandia in 2002, so I've been at this online worldbuilding thing quite a while now.

Word to the wise - don't try to run TWO such worlds, if you have a life. :-/

Mediawiki is easy to administer, and fairly easy to keep backed up and spam-free. But I am a web professional by day, so take my acclaim with a grain of salt :-). On the user side it's definitely easy to edit and extend.