Even the Government Tweets!

Twitter is now being used by state and local government agencies, and public institutions. This site, http://govtwit.com/ covers government Twitter accounts from all over the world, not just the US.There are over 2000 accounts, which you can access alphabetically through the LIST tab.
A keyword search is also available. It is tag based ( at least at the moment). You can get to individual "tweeters" through their agencies or institutions.