Examples of wikis created for teachers/learners: 

(Remember to open up the "side bars")

reference wikis:

     Engaging Students in Digital Writing --

    Rhetoric and Composition: A Guide for the College Writer --

     TV show wikis:    Lostpedia -- Heros wiki --

     Wikipedia -- the predecesor of all wikis

classroom wikis:

    Room 15 Wiki -- (elementary level)

    Book Club wiki's -- Ms. Boeser -- High School English

    Novel Study wikis -- Montana 1948 -- Speak -- character analysis --

     Mr. Hatten's English --