Weekend reading. The NYT pointed me to Many Eyes, a site for sharing of data visualization. You can upload a data set (or use an existing one), pick a visualization and publish it to the world. Many Eyes is part of one of IBM's fundamental research programs.
Some visualizations are the standard charts also available in PowerPoint, others are more unusual, for example tag cloud generators, and maps (countries, world) which are always tricky to create in PowerPoint.
A shame though that it is not possible (at least I have not discovered it) to take visualizations off the site and use them offline in your own presentation.