Google is rolling out a new search mechanism which will make it easier to find and compare public data. They have started with unemployment data. Now, if you go to the google search, and type in the following words -- unemployment rate -- followed by whatever state you want to see the information for, the first record that is returned should be a chart of the unemployment rate for that location. If you click on the chart, you will get an interactive record that allows you to compare the unemployment rate for your initial location with other locations in the US, including by county. See, e.g., the comparision for Massachsuetts and the U.S. as a whole: http://www.google.com/publicdata?ds=usunemployment&met=unemployment_rate... or for two counties within Massachusetts (Suffolk and Bristol) http://www.google.com/publicdata?ds=usunemployment&met=unemployment_rate...
Google plans to add other searches too; however, their initial ones are for population and unemployment rate. For more information, see the google blog, http://googleblog.blogspot.com/2009/04/adding-search-power-to-public-dat...