The Rivendell town Hall I belive is used for town meetings. It has an excellent meeting hall upstairs and a bit of a museum down stairs (notice the 3 stone heads). It is open and seems to be available to anyone who wants to use it as I saw when a guild showed up and proceeded to have a pep ralley before going off to the cross roads to hunt PKs.

Here is a link to Rivendell's web site: http://www.war-games.com/~town/