Why should a representative care about the opinions of people who aren't voting for her or contributing to her campaign? There are lots of opinionated people on the internet.
I simply picked the board of elections because they already are entrusted with the capacity to verify that a certain person lives in a certain ward or district. I suspect zip codes would not be fine-grained enough for local government fora, where this would be most useful.
They don't have to weight everything equally, but as I previously stated, politicians that actually want to do good and not just get re-elected (I hear some exist) might actually care about their precedent-setting decision and how it will impact non-residents.
I think there is certainly value in outside voices. Journalists and bloggers play that role now. I guess the issue I have is that any given district could get suddenly swamped by outsiders. Why not have it be the case that constituents would bring that voice in by linking to their post?
One idea that I have some sympathy toward is making the representatives responsible for moderating the fora as they see fit. They would then be judged at the ballot box if they pissed everyone off...or they would really skillful at creating false consensus.
I simply picked the board of elections because they already are entrusted with the capacity to verify that a certain person lives in a certain ward or district. I suspect zip codes would not be fine-grained enough for local government fora, where this would be most useful.