''do''hyki (http://www.cabezal.com/blog/archives/000721.shtml) behaves somewhat like a wiki, but stores its pages in a Groove peer-to-peer shared workspace; there's no central server. 

http://www.cabezal.com/blog/do-hyki.gif
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CategoryWikiImplementation

The link, when clicked, says "this part of the internet does not exist". Quite interesting I must say :-)