Determining if an address is within a radius of a zip code

Q: I need to take a list of vendors and be able to extract those vendors within a mileage of a zip code. For example, list all vendors within 40 miles of 44131. Is there a utility that will facilitate this?

A: The USPS offers several free web services that perform these functions. Go to http://zip4.usps.com/zip4/welcome.jsp and click on "web tools" in the lower left corner.