Both commercial and non-commercial wiki farms are available for users and online communities.
Many wiki farm companies generate revenue through the insertion of advertisements, but often allow payment of a monthly fee as an alternative to accepting ads.
A useful comprehensive comparison of wiki farms can be found on MediaWiki's site, at mw:Hosting services.
Online services which host wiki-style editable web pages.
This table compares general information for several of the more than 100 wiki hosting services that exist.