Google Sites:

Google Sites is a web and blog site that allows multiple users to access and use a single blog site. Each of the users has access to a new page and groups of users then have access to the blog sites. This is perfect for when collaborative work is being produced, especially in a classroom environment. In a workshop or convention type setting a workshop can be conducted with multiple users editing, changing or producing blog content while an audience continues to have access to the active site.

https://sites.google.com/