While on the topic of maps here’s a Microsoft Virtual Earth mashup — US Demographics Visualizer. It allows the user to map US census data by county. Map population, age, ethnicity, election results, and income. It’s not quite as responsive as the Competitive Edge Explorer, but if you’re looking to explore country-wide census data, then it’s worth taking a look at.
US Demographics Visualizer Using Virtual Earth
Visualizing the Uncertainty in Data
Data is an abstraction, and it’s impossible to encapsulate everything it represents in real life. So there is uncertainty. Here are ways to visualize the uncertainty.