21classes

http://21classes.com

This is a blog site that works well for educators.  It allows teacher control over published material and posted comments.  The site does not require student email accounts.  This is often a determent as many students don't yet have email or ones in which they can get to at school.  

Blogs foster comunication as they allow students to communicate with a larger audience and for various purposes.  They most certainly have value in the school environment.  Students can post blogs about assignments, respond to literature pieces, or share strategies for working through problems, etc.  The posibilities are endless.