If you're looking for a tiny, quick Wiki engine that DOESN'T need to be hooked up to a stinkin' database, look no further than Oddmuse!
Under active development for fifteen years, with thousands of instances up all over the intertubes, including the biiiiiig Emacs Wiki! Its core, four thousand lines of elegant, lovingly crafted Perl, can be extended with hundreds of modules, and writing your own is easy!
There are also a hundred CSS skins available to make your wiki's look fit its function.
If you have questions, join #oddmuse on Freenode; there are n00bs ready to learn and aulde-timers alike ready to talk the talk, and walk the wiki walk!
Google up Oddmuse and have your own wiki running minutes later.... or just click here!