Google offers a recently added feature (discussed on the Google blog in April here) that allows for both searching and visualization of public data.
There is no special doorway to this data; just search on "unemployment rate Philadelphia" (for example) in the plain old Google search box. The first link in the result list will be accompanied by a chart illustrating the latest data for your search.
When you click the link, however, you are taken to a larger interactive chart where you can compare the unemployment rate in Philadelphia with the rate in other cities and states.
The Google blog states that the visualization aspect of the public data search comes through their acquisition of Trendalyzer, a program that enabled the animation of statistical data.