Okay, so while working the day job I was looking for something on how to improve a customer's store-finder page (it does a straight lookup of the first three digits of their ZIP code now...lame). I've found formulae before to find the distance between two sets of latitudes/longitudes (the haversine formula is the easiest to implement) but this one was an application I had never considered - matching up orders from infomercials to the TV station and broadcast that might have prompted their order.