Wiki

https://www.wikipedia.org/

Search
http://www.wiki.com/

How
http://www.wikihow.com/

a
http://www.wikia.com/

Spaces
https://www.wikispaces.com/

Edu
https://wikiedu.org/blog/

Map
http://wikimapia.org/

Category
https://en.wikipedia.org/wiki/Category:Wikis
https://en.wikipedia.org/wiki/Category:MediaWiki_websites