We have something similar called the Superintendent's Communication Council, however I have been trying to slowly turn them into ambassadors for our school district and have armed them with materials, etc. however haven't gotten to that "next step" to turn them into pro-active advocates. Off of the Communications Council I also have a couple of key people who are parents at individual schools that have a great email network. If an issue arises, or there is a question, I get to respond quickly and then the information gets out fast and a couple of times it has been to our advantage to clear up misinformation before it hits media. These other key people are really the grassroots of the parent/communication level, but I don't have a name for them. Email seems to be the best way to reach these people informally, and I don't send out structured messages (although they are on my district-wide parent email list for our enewsletters) as they are a very keen audience and can turn on a dime if they feel that they are being "marketed" to. We have a good relationship this way and they trust the information flow at that level.

Your idea of turning them into a key communicatort network or getting them on critical school district committees is a good one.
   If you have a school support ballot measure anywhere on the horizon, you might want to turn this group of citizens into an advocacy committee to do all of the things the district can't do to get the measure passed.