Laconica (pronounced "luh-KAWN-ih-kuh") is a Free and Open Source microblogging platform. It helps people in a community, company or group to exchange short (140 character) messages over the Web. Users can choose which people to "follow" and receive only their friends' or colleagues' status messages. It provides a similar service to sites like Twitter, Jaiku, and Plurk.
DestroyTwitter is a compact though robust Twitter application built to run on Mac, Windows, and Linux using Adobe AIR. It consists of a series of canvases that constantly update to keep tweets up-to-date using notifications that appear when a new tweet arrives.