Check out these wikis to get ideas and see what other teachers are doing:

http://www.kentisd.org - the ISD main website

http://educationalwikis.wikispaces.com/ - a list of articles, and actual wikis from schools and classrooms.  Also a place to post and share ideas about educational wikis.

http://webtools4u2use.wikispaces.com/ - a wiki for educators to learn about cool new web tools.

http://web2-sandbox.wikispaces.com/ - a place to learn about and experiment with web-based tools that support 21st century teaching and learning.

http://www.wikihow.com - the world's largest how-to manual, offering solutions to the problems of everyday life.

http://blip.tv/file/246821 - Not sure what a wiki is?  Watch this cute video to find out.

http://flatclassroomproject.wikispaces.com/  A global hands-on site to foster collaboration for teachers and students using Web 2.0 tools.

http://rescue.wikispaces.com/  The R.E.S.C.U.E.  group is a consortium of ISD's trying to share digital text.  Lots of information here about copyright, district forms and a link to the file sharing list.

http://region3atc.pbwiki.com/  The Region 3 Assistive Technology group (western lower Michigan) has some useful assistive technology information.

http://jfriesen.net/profdev/literacies.html - many education wiki's listed on this website.

http://mswebster.wikispaces.com/ --second and third graders who are using technology to help share with the world, what they are learning.

http://wiki.woodward.edu/hannalee/doku.php?id=hannalee - a 5th grade wiki.  Students contributed information the novel "Turn Homeward, Hannalee"

http://studyingsocietiesatjhk.pbwiki.com/ - a middle school wiki based on the topic of societies.  Different groups of students posted information on different topics.

http://aristotle-experiment.wikispaces.com/ -- a high school wiki

http://eatme.wikispaces.com/ - a wiki used by a teacher for collaboritive story telling and persuasive writing.

http://monsonclassroom.wikispaces.com/ - Mr. Monson's  5th grade classroom wiki.

http://libraryzone.wikispaces.com/ - students work collaboratively on research projects.  Create information resources, write stories and exchange their ideas through wiki, email and discussion pages.

http://hmtech.wikispaces.com/ - Houghton Mifflin resources by grade level.  

http://educationalsoftware.wikispaces.com/ - resources on different educational software and Web 2.0 tools, most of which are free.