I use a program called NeoTrace Pro. It has latitude and longitude of routers, servers, etc. Coupled with a mapping site, you can get a rough idea where that particular IP is located. The only exception of course is dialup IP addresses. They're usually centered on the location of where the modems are located, which in many cases is the same location of the ISP.
Yeah, maybe that's the same one I saw a year or two ago. I was really impressed, and didn't like it at the same time. (the privacy thing)