Visualization applications can enable interactions between people in powerful and unexpected ways, as illustrated by the following two personal experiences.
In the spring of 2003, the first author created PostHistory, an application to visualize e-mail archives of individuals. (1) Given the personal nature of the data, it was assumed the archive owner would view the data alone. Indeed, during a usability study, the experimenters carefully explained to participants that no one other than the owner would have access to the visualizations. Yet, as soon as users had access to the application, they began finding ways to share the resulting images. Users mailed screen captures ...