Neal Stephenson operates a wiki for explanations related to his new book. In terms of its goal, it's something like a lexicon guided by and oriented toward his book, which takes up connections and questions from the book and elaborates on them further, but can certainly also go beyond that to link in additional content. Actually quite an interesting idea, even though it partially duplicates information from Wikipedia - the approach is simply a different one. Inter-wiki links would probably be appropriate in the long run anyway, unless all content from Wikipedia is supposed to be replicated there permanently. Here's the original article.