This application from CDX Technologies creates a demographic report for all US zip codes within a specified radius of a central zip code. Pay $.01 per zip code using your credit card or PayPal (minimum charge of $9.95) or use your CDXStreamer account for lower costs and no minimum charge. Up to 20,000 zip codes can be processed in a single report.
An example of an output data file can be downloaded here. You can analyze the example and other demographic lists created with this tool by downloading our free Demographic Report Template. Definition of the data fields listed can be found here.