For an elementary school, which is the level at which I teach, I like the Hanalee Book Wiki. The information included on the different pages was useful, well-organized, and added more detail to the story.
For personal use, I think wikiHow is a lot of fun. There are all sorts of useful how-tos as well as some funny ones.
Having a wiki as a school website, like Arbor Heights Elementary School Wiki, is an intriguing idea. I am not our school webmaster, so making this switch would not be my decision.
Examples of Educaitonal Wikis is an interesting site for someone who is planning a wiki and needs ideas, but just having an alphabetical list of sites makes perusal difficult. The search function doesn't work to search for wikis on specific topics.
I would be most inspired to create my own wiki by the Hanalee Book Wiki. As a media specialist, I could see this wiki being created by a classroom under the guidance of their classroom teacher and me, the media specialist. I don't see the students for enough time to make it a project they would complete only with me. I have a fixed schedule in the media center, so I cannot schedule more time with a class or meet with them as needed. My schedule is booked with other classes. So, there's one hurdle. Another hurdle would be finding a teacher who is interested in collaborating on a wiki. Since I only meet with each class for 45 mintues a week, much of the work with the students would fall upon her. I could collaborate with her on our own time for planning and for technical know-how. Students could complete some work in the media center, but most of their computer time would have to be with their classroom teacher. I think a wiki on a book would be valuable to students and would be worth the fight.