Oddmuse!

MoinMoin is an advanced, easy to use and extensible WikiEngine with a large community of users. MoinMoin's storage mechanism is based on flat files and folders, rather than a database. MoinMoin supports plugins and can be extended via Macros and Actions. It also uses the idea of separate parsers (e.g. for parsing the wiki syntax) and formatters (e.g. for outputting HTML code) with a SAX-like interface between the two.

Hatta is a wiki engine – software that lets you run a wiki. It requires no configuration and can be easily started in any Mercurial repository.