DataWeb & DataFerrett
DataFerrett is a data analysis and extraction tool to customize federal, state, and local data to suit your requirements. Using DataFerrett, you can develop an unlimited array of customized spreadsheets that are as versatile and complex as your usage demands then turn those spreadsheets into graphs and maps without any additional software. (from website.) Open link with Internet Explorer or Mozilla Firefox, Chrome does not work.
Open source, from U.S. Census Bureau