The Community Bar is groupware supporting informal awareness and casual interaction for small social worlds: a group of people with a common purpose. Its conceptual design is primarily based on a comprehensive sociological theory called the Locales Framework, with extra details supplied by the Focus/Nimbus model of awareness. Design nuances are strongly influenced by observations and feedback supplied by a community who had been using both the Community Bar and its Notification Collage predecessor for a total of five years. As a consequence, Community Bar’s design supports how communities of ad-hoc and long-standing groups are built and sustained within multiple locales: places that offer a group the site and means for maintaining awareness of one another and for rapidly moving into interaction. This includes a person’s lightweight management of his or her membership in multiple locales, as well as ones varying engagement with the people and artefacts within them. Categories and S...