I live on a dirt road in the mountains. There are two (was three) other full time residents, plus a few part timers. I have thought of setting up a twitter account just for us, to report winter driving conditions. We have all had the experience of being away from home when a storm comes in, and we call each other to find out who knows how deep the snow is, whether we should plan on snowshoeing in or put on the chains or what. Twitter would be fine for this, very low traffic. 140 chars would be far more than necessary.
I follow some gun rights forums which occasionally tweet developments, usually one or two a week at busy times. Again, twitter is just fine, a simple way to broadcast interesting news.
I signed up to follow a Linode account, but it is disappointing, mostly being links to fresh HOWTOs. Not many, one or two a day, but I'd rather sign up for just "network down" kind of tweets and skip the non-urgent stuff.
What makes it useful is not having idle chitchat on them, just tidbits of timely info. Maybe some day I will set up the dirt road account, but I'd have to get the other residents to sign up with twitter :-)