A
Wiki, written in
Python. It uses the
filesystem for storage of pages (as opposed to a database), employs caching to speed up page serving, has support for serving multiple wikis through a single server process. MoinMoin also does page locking, to prevent concurrent edit smashing.
For ideological reasons, it does not support forums: it is a resolutely wikish wiki.
MoinMoin can use Apache, Twisted or its own Python built-in web server. Since it is written in Python, it runs under Windows, MacOS and Linux, plus other more exotic platforms.
I find it attractive for its simplicity. Not reccomended for large complex sites, which would probably work better with a proper database-backed CMS, such us our own beloved Everything2 or the MediaWiki system used by Wikipedia.