There appears to be several ways of categorising Wikis.

Dan Woods and Peter Thoeny in their book "Wikis for Dummies" list four types:
Content-focused Wikis, Process-focused Wikis, Community Wikis and Ease-of-Use Wikis.

Mark Choate in his blog defines two types used by organisations:
Collaborative Wikis and Knowledgement Management Wikis.

And lastly, Media-Culture Wiki cites three types:
Educational Wikis, Social Wikis and Corporate Wikis.

From, netoCiety's point of view, which categorisation, if any, is most appropriate?