The technology is there to do this kind of thing. Now it's more a matter people taking advantage of it. Look at twitter and how most people use it through things other than the website.
I recently worked on a site where users responded to and interacted with a forum through email. The integration is here... it's just in the early adopter phase. The real question is what are your projects requirements and how do you interact with something like that.
On an episode a while back, there was a suggestion to have the content of one's site delivered to the users by way of email, widget, RSS, etc. In other words, a user would only have to visit a site once to create an account and perhaps adjust settings, and then would interact with the site remotely. I really like this idea and would like to hear more about it. It seems as though this is where the internet is headed, removing barriers to participation.
Some examples might be:
Nick
http://www.WaxArtistic.com
www.WaxArtistic.com