What is a Wiki? The most well-known example is Wikipedia, and not so well-known Wikibooks. You can create an account and edit content on both of these pages. Never fear, there are plenty of administrators that can control editions and modifications…too a point.
Wikispaces is a wonderful way to share the concept of a Wiki with your students, while giving them Web Space for creating their own content. Although blogs can be a great tool for students to share digital content, Wikis seems to provide teachers with enough flexibility in creating student web pages (See account support here>>>http://www.wikispaces.com/help+Teachers )
Create your own Wikispace. Once you are in a school, you can apply for the educators version and create users for all your students, create pages for them and UNLEASH them!