As an example take this
UseModWiki is an implementation of the original Wiki concept 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 (see WhatIsaWiki). This site exists to test UseModWiki and to attract suggestions for future improvements. See SiteList for a large list of other sites using UseModWiki--a good example site is the [Meatball wiki] which discusses online communities.