I set up a google form entitled "EduTwits" for a workshop. Some of my twitter friends helped out and filled in their info, thanks to everyone who did. The workshop is over but the form still works! All you do is fill in your Twitter ID, country and blog or website url. The sheet automatically updates.
I'd also suggest trying Group Tweet for working with groups. They do one beyond a basic group tweet in that users can use it like a Tweetserve (listserv). Kind of need and could be very useful for classes or other collaborative groups.
Someone (sorry no attribution) tweeted about this the other day.
A few of us also started a wiki for our twitter network to have more contact info for our twitter friends - it was originally set up in case a twitter outage, but as that happens less and less, it's now become sort of a clearinghouse for our contact info. You can find it here: http://twitterbrainstorm.wikispaces.com - request to join!