MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia. It is now used by several other projects of the non-profit Wikimedia Foundation and by many other wikis.
Trusted by 8,000 businesses, Confluence is the leading collaboration software and enterprise wiki for intranets and knowledge management. Free 30-day trial.
XWiki is a powerful Open Source collaborative platform allowing companies of all sizes to save time and money while enhancing collaboration on both team and organizational level. Being focused on efficient communication and collaboration, XWiki redefines the value of business...
wikiCalc is a wiki-based spreadsheet developed by Dan Bricklin and released under a GPL license. SocialCalc is co-developed with Dan and Socialtext, released under SPL and is being integrated with Socialtext Open.