Wikis Wikis In Plain English Wikis in Plain English is a great explanation from Lee Lefever at CommonCraft
Wikipedia Wikipedia is a free content encyclopedia, written collaboratively by people from around the world. The site is a wiki, which means that anyone can edit articles, simply by clicking on the "edit this page link". Don't forget Simple Wikipedia which may suit your primary aged students better.
National Curriculum of SA The National Curriculum of South Africa years 10-12 can be found online in a Wikibooks Wiki.
MiddleJ Wiki Our first try at making a Wiki, our Middle J Wiki is based around minibeasts.
pbwiki Peanut Butter Wiki, pbwiki is where you can make your own free wiki. To remove the adds costs money though.
Wikispaces For Teachers Wikispaces for teachers is another free to education place to create your own wiki. It is a little more flexible than pbwiki and doesn't have the adds that pbwiki has.
Terry the Tennis Ball Terry the Tennis Ball is a choose your own adventure type story built on a wiki that my grade 3/4 children are having a lot of fun with, (though I wonder about my teaching of spelling and punctation :).
Geelong On The Move Geelong On The Move is a wiki that my grade 3/4 children used to develop a space about the history of Geelong.
Getting Started with Wikispaces Getting Started with Wikispaces is a set of tutorial notes I wrote to help you set up your own wikispace.
Warlick's Wiki David Warlick is another of the gurus in this whole field of the read/write web. Warick's wiki is a great free link out to many of his presentations as well as being a great wiki exemplar.
Wiki Walk Through The Wiki Walk Through from Teachers First is a neat website look at all things wiki.