http://www.kinhost.org/wiki/ - The Kinhost Wiki -- what you're reading this page in right now. Allows people to just walk in and start contributing, with a tiny learning curve but plenty of advanced features for the stalwart contributor. Awesome :) -- but I didn't write it. See "Contributions" for links to the source code project.
http://crisses.org/ Our Wiki (Auto)Biography project - intended to be a group collaborative project where relatives and friends of ours can add their own input and perspective to events in our life. Hasn't been opened yet, so no one has contributed as yet.