Wiki farms are a great way to get involved in a wiki community or start your own wiki. Wiki farms usually allow a single login access to multiple wikis, and often allow a global search across all hosted wikis.
The Alexa ranking given indicates how popular the website is compared to all other websites on the Internet with a ranking of 1 being the most popular website, 2 being the second most popular, etc.
1. Wikia
Features: Subdomain support, RSS support,Wiki creation subject to approval
Alexa Rank: 553 (12/21/07)
3. PBwiki
Features: Business and Education focus, subdomain support, private wikis, RSS support
Alexa Rank: 4,853 (12/21/07)
4. Wikispaces
Features: WYSIWYG editor, Subdomain support, RSS support, Blog import integrated with Blogger.com and Typepad, customized themes
Alexa Rank: 9,250 (12/21/07)
5. Wikidot
Features: Subdomain support, RSS support, Customizable themes, Revenue sharing,
Alexa Rank: 13,827 (12/21/07)
6. Central Desktop
Features: Business-oriented, WYSIWYG editor, templates, RSS Support, Authorization control
Alexa Rank: 25,834 (12/21/07)
7. SocialText
Features: Business-focused wiki, WYSIWYG editor, Private pages
Alexa Rank: 39,854 (12/21/07)
8. StikiPad
Features: Focused on being a personal wiki, subdomain support, RSS support
Alexa Rank: 62,924 (12/21/07)
10. SeedWiki
Features: WYSIWYG editor, subdomain support, widgets and plugins for additional customization
Alexa Rank: 101,308 (12/21/07)