What is a wiki?  

A wiki is a website that allows multiple users to edit it's content.

This can allow collaboration on a glocal scale..

Building and Sharing Knowledge 

Wikipedia became successful because (among other things) the main goal was to generate public knowledge.   We can borrow this model for the education world: to build our subject knowledge base.  

Students work to co-write, discuss and co-edit content.  

This can be in the theme of...
1) Writing and sharing poetry 
2) Creating content based wikipedias (Especially valuable in Science or Social Studies)
3) Co-writing a story or movie script
4) or more... 

Using PBwiki

PBwiki is a online web hosting wiki server.  As an educator you can sign-up with pbwiki for free and start developing a very versatile wiki for any purpose.

Get to know PBWIKI task..
Try setting up a pbwiki on a topic for your students.

Here is a link to a "How to" Slide Show.  If you want a paper version you can download the ppt and print the slides.