The agency world has taken to Twitter in droves. Agencies themselves are tweeting, of course, although most are a stream of self-serving kudos. The more interesting stuff comes from agency folks themselves. Creatives, particularly writers, are reliable sources of droll updates that take the ironic, deadpan view of life. Strategists are eager to be the first to tweet the link to the latest Kim Jong-Il Tumblr or article on Mashable about some startup you’ve never heard of and probably never will again. On the media side, tweets are more buttoned down and business-like, interrupted by frequent Foursquare check-ins at airports. We came up with our five favorite agency Twitter accounts, representing a cross-section of the agency world.