G+ Ripples is a visualization of information flow that shows users how public posts are shared on Google+. Unlike other social network visualizations, Ripples exists as a "native" visualization: it is directly accessible from public posts on Google+. This unique position leads to both new constraints and new possibilities for design. We describe the visualization technique, which is a new mix of node-and-link and circular treemap metaphors. We then describe user reactions as well as some of the patterns of sharing that are made evident by the Ripples visualization.

How do people use an enterprise file-sharing service? We describe patterns of usage in a social file-sharing service that was deployed in a large multinational enterprise. Factor analyses revealed four factors: Upload & Publicize (regarding one's own files); Annotate & Watch (add information to files and maintain awareness); Discover & Tell (find files uploaded by other users, and communicate to additional users about those files); and Refind (re-use one's own files). We explore the attributes of users who score highly on each of these factors, and we propose implications for design to encourage innovation in usage.

Most knowledge repositories focus on the role of knowledge-creators. In this paper, by contrast, we examined the work of Lurkers in an enterprise file-sharing service, and we compared their lurking behaviors to the lurking behaviors of users who uploaded files (Uploaders), and users who contributed metadata about files (Contributors). For comparability, we restricted our analyses to the consuming behaviors that are common to the three roles (Uploaders, Contributors, and Lurkers). Independent principal components analysis showed highly similar seven-factor solutions of lurking activities across all three roles, although the relative emphases of those factors varied across roles. Uploaders tended to view and download more groups of files, showed less emphasis on searching for files, and tended to work directly with the file-sharing application, unmediated by external applications. Contributors showed the opposite pattern: more emphasis on searching and responding to recommendations from other users, often via a form of remote access. Lurkers' lurking behaviors were less intense, and showed little difference in emphases among the lurker factors. We use these results, and the published research literature, to motivate a research agenda for lurkers in social media.

We discuss the design and usage of "Wordle," a web-based tool for visualizing text. Wordle creates tag-cloud-like displays that give careful attention to typography, color, and composition. We describe the algorithms used to balance various aesthetic criteria and create the distinctive Wordle layouts. We then present the results of a study of Wordle usage, based both on spontaneous behaviour observed in the wild, and on a large-scale survey of Wordle users. The results suggest that Wordles have become a kind of medium of expression, and that a "participatory culture" has arisen around them.

We describe a social bookmarking service de-signed for a large enterprise. We discuss design principles addressing online identity, privacy, information discovery (including search and pivot browsing), and service extensi-bility based on a web-friendly architectural style. In addi-tion we describe the key design features of our implementa-tion. We provide the results of an eight week field trial of this enterprise social bookmarking service, including a de-scription of user activities, based on log file analysis. We share the results of a user survey focused on the benefits of the service. The feedback from the user trial, comprising survey results, log file analysis and informal communica-tions, is quite positive and suggests several promising en-hancements to the service. Finally, we discuss potential extension and integration of social bookmarking services with other corporate collaborative applications.