Geographical Information Systems
Scott,
That site is being run by a system called "HAHTsite", which I discovered by breaking it and looking at the error message. Googling "HAHTsite" turned up their Web site at http://www.haht.com/.
This category of software is called "Geographical Information System", or "GIS", and a search on the term should turn up plenty of vendors--it's a popular category these days. One of the better-known vendors is MapInfo (I think HAHTSite may incorporate MapInfo technology).
Hope this helps....
--Robert