Chuq van Rospach shares some insight on the long battle to make email work better socially: In part one, he argues that any attempt to codify good behavior will fail to create utopia, but may influence future tools and enough people to be worth trying. In part two, he says the only real way to fix problems in email is with tools, not by trying to influence behavior, if only because there are too many people using email for any lasting consensus on how to use it.
In the comments to Chuq's post, there's a link to a really interesting proposal to make mailing lists easier to use - Luis Villa: "Mailing lists are parties. Or the should be." The idea here is that the tools should help us give and receive some of the social cues that make parties successful where mailing lists aren't, like politely showing someone that they're boring or annoying you (by leaving the conversation), or quickly finding the interesting conversations (by seeing who and how many people are paying attention to it).
I really like Luis' suggestions, because you could do this with mailing list software today.