If you are looking for an EASY and very cool way to promote community amongst your interest groups, I have found TabUp to be an outstanding resource. If your school district does not provide you with your own web presence FREE TO YOU, and you would like to create a private, semiprivate, or open destination for communication, TabUp can provide just what you are looking for.
With features like a shared calendar, forums for discussion, links to various web resources, and the ability to make this modrated or invite only ALL FOR FREE, I can`t think of a school group, sports team, or common interest group that would not find some use for this service.
Please take a look, and add your thoughts to this page. I will be automatically notified of any changes or additions, and will be sure to act on valid suggestions.