Are you gonna setup a wiki anytime soon? Checkout the WikiMatrix site which allows you to compare various wiki software projects according to a huge amount of criteria.
My favorite has always been MediaWiki (probably because I occasionally write for the Wikipedia). I use that for both, the Unmaintained Free Software wiki, as well as the Crazy Hacks wiki (both need some more love and contributors, hint hint). I'll checkout some of the other wiki software projects soon, though...