UseMod

http://www.usemod.com/cgi-bin/wiki.pl?UseModWiki

UseModWiki is an implementation of the original Wiki concept [1] created by WardCunningham.

A "wiki" is a website that is collaboratively edited by its users, including the ability to change text written by other users.

btw, UseMod is also available as a DeBian package: http://packages.debian.org/unstable/web/usemod-wiki