Wikis?

What are some of the pros and cons of using a wiki? What are some projects people could do that would use wikis?

Some of the cons of using a wiki is that the students might not know how to use the wiki properly or even use it at all. The pro of that theory is that they can teach each student how to use a wiki properly. Or maybe the wiki might be a little too complex for some of the students, because i know myself that i was a bit bewildered when i barley stated using it.
The other upside to using wikis in the class room more often is that we know how to use other sources of using websites so it helps us gain knowledge. Over all i think the wikis would be a great addition to our class projects, we'll have more options and varieties for projects.