Google Groups 

With Google Groups for Business you can enhance messaging and collaboration among your users. With this service, users can:

Manage their group memberships, so they can tailor email communications to their needs, without having to make requests to your IT department.
 
Create their own groups, so they can further customize their communications -- without the need to contact your IT staff. You can give this privilege to users and remove it at any time. If you let users create their own groups, they can manage their groups to control who can join, send messages, invite members, view members, and view discussion archives.

Benefits for Educational Institutions
Instructors can improve communications among students by creating groups for their classes, subjects, and grade levels. Students can use groups to reach other students in their classes, sports teams, clubs, and extracurricular activities.