The recent development and distribution of interactive pervasive computing systems, especially those incorporating digital public displays, facilitate a variety of new interactive scenarios in shared public spaces where people gather and spend time to enjoy a social experience. Integrating novel interaction mechanisms related to the sharing and listening of music with digital displays is a good example of the potential of using current technologies to enhance physical and social spaces. This paper explores the design and impact of shared situated interactive systems, combining public display installations with a collaborative music player. To explore the design space of these systems, we conducted two studies involving the deployment of a particular system at different venues. The analysis of our results allowed us to identify specific (group) interactions and events, which were fostered by the system under consideration. Based on these outcomes, we propose a set of features that should foster further engagement with such systems and promote new ways of social interaction.