User blog comment:Godisme/Wikia Alternatives/@comment-791183-20100930123133

A lot of wikis are moving to ShoutWiki. It's free and will become just as popular - and the staff are incredibly friendly.

The "MediaWiki" option actually requires buying a domain and using a server, then manually installing MediaWiki on it. Unless you are prepared to use your own money and are prepared to use up a lot of time installing MediaWiki, you should go with ShoutWiki.