Map an area based on the number of business establishments in a given industry: Custom search > Geography > Map based search. Combine this with another parameter, such as industry (NAICS or SIC code).
Features include: " menus to select your type of business and potential business location. An interactive map that allows selection of the area to explore for business opportunities, including comparisons to neighboring areas. Dynamically generated,[...] county- and city-level reports"
"Find geographic data and products such as the TIGER/Line Shapefiles, KMLs, TIGERweb, cartographic boundary files, geographic relationship files, and reference and thematic maps."