I've finally had a chance to look at Many Eyes, a new project from the CUE lab in IBM. The service itself is running and you can try out the application on alphaWorks Services. Think of it as a charting and data visualization tool, similar conceptually to the chart tool in Excel, but much richer and available as an online application. The types of visualizations include: World & US maps, Line graphs, Stack graphs, Bar charts, Block histograms, Bubble charts, Scatterplot, Network diagrams, Pie chart, Treemaps, and more.
The Network diagrams example below is conceptually similar to CNet's The Big Picture portlet (provided by Liveplasma) on this example page. You create a spreadsheet of names or topics and list the relationshps between each entry, typically in a big matrix. CNet also does Treemaps under What's Hot.
I posted an example of a network diagram from Many Eyes below. This is only a thumbnail to go to the actual tool itself, but its a start. I really wish I could embed the actual applet in here somehow.