Sure, a manufacturer of faucets may have a really dedicated fanbase that is both IT literary AND passionate enough to populate a wiki about 1/2 inch pipes, but many "community" efforts fell to the floor like a sack of potatoes.
Open Site - Another blend of wiki and reviewed content, Open Site is slanted toward more of a popular content direction, with information about games and current events taking primacy over science and philosophy.
While it does have a very large medical dictionary area, it also includes other large sections like a legal dictionary, a Wiki encyclopedia and a directory of idioms and acronyms.
Operating on the idea that everybody knows something someone else doesn't, our wiki system allows you to easily add your own watch reviews, recommendations, links and much more.
Genealogy Today is a privately created website that has a search engine, articles with research tips, and a wiki that you can use to contribute your own information.
Thankfully, the good people at Limewire put up a very useful wiki page that discusses this issue, helping you overcome the problem of not being able to connect.
Wiki How has a "How to Make a Turkey Pop Up Card" tutorial that uses paper cutting techniques to create a very memorable Thanksgiving greeting.
LoveToKnow Antiques and Collectibles uses the wiki system, which allows anybody to edit existing articles or even add new articles to the site.
According to the site's wiki, there are underground practitioners who will do modifications which an ordinary doctor would likely refuse.
Here's a description of them at the Wikipedia (http://en.wikipedia.org/wiki/Help:Footnotes)