Wiki Hosting Solutions -

MediaWiki MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia
DokuWiki DokuWiki is a standards compliant, simple to use Wiki, mainly aimed at creating documentation of any kind.
PmWiki PmWiki is a wiki-based system for collaborative creation and maintenance of websites
WikkaWiki Wikkawiki is a flexible, standards-compliant and lightweight wiki engine.