I'm pretty sure if people had to give up something to get into a town hall meeting, you'd easily be able to weed out riffraff who don't want to actually gain information from the discussion. Now, it might be unreasonable to charge money for access (although I wouldn't oppose it), but what if you simply told people to fill out a form with their name and address, and show valid ID? Would that raise the "price" enough to bring some civility to the debate, and maybe tone down volume of the misinformation?
A lot of comparisons are out there, by the way, with anti war protests and their rancor. In a way, that's true, but those protesters generally kept their protests to the streets - they were seldom allowed into the "meetings" or "discussions" Bush and other Republicans held to preach to their base.