Hello Jeremiah,

Welcome to the UT!

Mapquest is the first thing that comes to my mind, and they have an Enterprise Toolkit that can be accessed across the web. I have no experience with the toolkit, and I'm sure it's not cheap...

http://www.mapquest.com/cgi-bin/ia_find?link=b2b/b2b_our-services_enterprise&uid=uazew4l141i1gdpa:2xhubghwzl

>Does anyone have suggestions on software or a database that can be used to calculate the driving distance between two zipcodes. We have used ZipFind but that just uses the lattitude/longitude to calculate distance. We need to calculate driving distances. MS Mappoint does it but it's way to slow. The US Postal service doesn't seem to sell information that contains distances, they just have lattitude/longitude of the center of the zipcode. Any suggestions?
>
>Jeremiah Johnson