There are a lot of affordances for wikis in the classroom.  I have used them and found that they are a great treasure to deposit a bunch of math concepts on.  Students really have had a lot of individual fun on them as well.  My first experience with them was in the summer of 2009.  I had my students simply use them to work on tests together without talking.  Each group had their own page and would collaborate by putting down the answers and members would either change the answer or simply do the other problems. I tend to use summer school to experiment with these types of technologies without any formal training.
My next experience with using a wiki was to redo my home page for school.  It gave me more freedom and it was easier to use.  CHECK OUT MY OLD SCHOOL WIKI.  Again, the whole idea of the wiki was still in its infancy in my mind and I really had not figured out how to use it well.  Without enough time to see the benefits in education, I really was only playing around with it so that I can learn it and hoping some sort of lightning bolt of knowledge would hit me.  I was also learning so many other tools at the time that I had no idea which were good or bad.  They just all seemed new and fun and I wanted to introduce the students to all of them because I knew other teachers would not.  This turned out to be a very bad thing when trying to promote change in a classroom.
The last time I used a wiki in class, I had the students working on it.  They were each in charge of posting our notes on it each week.  For each lesson, they were to link a video, a picture summarizing the topic of discussion, a game site(if found), and a link to definitions of the math words learned.  It proved to be too much management for me and a lot of extra work for the students.  The idea was for them to be creating a hypermedia presentation for reference.  Students would then build on it from each class and each semester.  I did not feel I had enough time to teach a wiki and teach the curriculum.  I now know that I do.
If this class has taught me one thing, it is that scaffolding is a very powerful principle in school.  I can, and probably will, go back to the wiki idea.  However, this time, lessons will be scaffolded in a way that it will not only teach the students the layout of a wiki, but allow them to creatively add on to it as well.  I do not have to manage it as I thought I did.  I would rather let it be more of an organic thing.  As time goes on and more people add to it, more will want to add to it and make it better.  It could ultimately end up being a great piece of work.
Stay tuned for Wiki 2.0 in my classroom, it might take a while, but it could prove to be one of the best references in Loudoun.  Especially, if I reach beyond the school walls and have other schools participate.