GikiWiki is a minimalist wiki written in ObjectiveCaml. It has very few features as a design principle: it uses the file system for page storage and an external version control system (currently, RCS and Perforce are supported).
I created it because I liked WardsOriginalWiki, but disliked the idea of running Perl from a web server, and couldn't find a suitably minimalist alternative. I've attempted to keep the spirit of WardsOriginalWiki while making some small design enhancements (such as a Preview button).
http://wiki.woozle.org/GikiWiki