The user-friendliness of the wiki makes it available for a multitude of uses in education and in the classroom.  The collaborative nature it possesses makes it invaluable in communicating with a group or a few people.  Here are a few uses that you might find interesting:

Classroom Use:

Study Guides

Adaptations

Adaptations 2

Missouri History

Reading Groups

Mules Reading Group

Cardinals Reading Group

Tiger Reading Group

Student-Centered Classrooms

Fractions

Save Fred 

Grade 6 Online Medical Clinic

High School Literature AP Classes 

Cooperative Learning 

Wikis in a K-12 Classroom

Portfolios

12th Grade Math Portfolios

Syllabus

Education W505 

Parent/Community Communication:

Parent Discussion

Katrina Help

District Sites: Arbor Heights Elementary  

Collaboration

School to School

Thousand and One Flat World Tales Project

Teacher to Teacher

Administrators:

Faculty Book Study

The Daily 5 

Collaborating on School/District Documents

Curriculum Planning Wiki

PB Wiki Teachers' Videos