Have you heard about Edmodo yet?
It is the coolest thing ever! In short, it is facebook for school.
You create groups (basically your classes) students then join those groups. You can send out assignments, have students turn stuff in, and grade it all through this site. It automatically updates a calendar for students, and you can even set it up to recieve text alerts!
The best part - my students are enjoying it and actively using it!
view original video posting here
image courtesy of edmodo.com