Robert Barta forwarded a link to Protovis: A Graphical Approach to Visualization.
Protovis composes custom views of data with simple marks such as bars and dots. Unlike low-level graphics libraries that quickly become tedious for visualization, Protovis defines marks through dynamic properties that encode data, allowing inheritance, scales and layouts to simplify construction.
Protovis (Javascript + SVG) + topicmap backend + your imagination = The Next Big Thing In Topic Maps?
Examples include maps and a number of other starting points for visualization of data sets.