[DoronS]

Our team uses a set of email mailing lists for our communications. We have what we call the "main group," where meeting announcements, general logistics information, and engineering discussion take place. Then, each division of the team has its own mailing list (programming, marketing, animation, the FTC subteam, etc) for division-specific discussion. Finally, we have a mailing list for the EC (executive positions) where more high-level team decisions are made.

Now that I write about all these groups, it seems like a lot to keep track of, but when each division lead administers their own group, it works out fairly well. Of course, none of these groups are exclusive to members of a single division, and people from multiple divisions are usually part of every mailing list. A benefit of this system is that receiving messages from a particular group is entirely voluntary, and people only sign up for the mailing lists that they are interested in.
If you're interested, we generally use google groups to administer the mailing lists.