There's a couple I've seen--but I couldn't comment on how effective they are. Huntington Woods, WI has one that makes recommendations to the City Commission (http://www.hwmi.org/residents/boards_commissions_and_committies/communic...), as does Hillsborough, CA (https://www.hillsborough.net/294/Citizens-Communications-Advisory-Committ), North Liberty, IA (http://northlibertyiowa.org/government/commissions-boards/telecommunicat...) and Wauwatosa, WI. I'd be willing to bet there's a bunch out there.
When I was at Reno, we had a sub-committee of the Council who provided a similar function, using two of the Council members who had a communications background. I also had "round table" meetings on a quarterly basis with lleaders of local PR firms that had government and nonprofit clients, where we would discuss community-wide issues that was very helpful. The local government communicators in the area would also join together for editorial board meetings.
I had uploaded our communications plan here: https://icma.org/documents/strategic-communications-plan