I was looking for some Wiki software the other day that I could use to handle a large volume of static content I had with my old CMS that doesn’t really fit into WordPress very well. I settled on the excellent DokuWiki.
Unlike most Wiki software, DokuWiki doesn’t use a database but instead stores all data in plain ASCII files. Not sure how well that would work for very active Wiki’s, but as I’m using it as a read-only application anyway (i.e., I’m the only user allowed to make edits), its a nice, clean way for me to set up my content. And it was trivially easy to install.