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.
Social Mention is a social media search engine that searches user-generated content such as blogs, comments, bookmarks, events, news, videos, and microblogging services.