There is a site called geourl.org. It defined a standard for embedding location info into a web page, and has a search engine to allow people to search for web pages related to sites around a location. In the middle of 2004, it went away for about a year.
I had been using the XML data feed from geourl.org as part of the data that mapper.ofdoom.com uses. When it went away, I missed it. Eventually, I started playing around with writing a backend to do the same thing - polling a collection of web pages to check for updates to the location info they contain, and allowing the dataset to be searched by users, with the results available in as many formats as I could think of. I had planned on using the backend to track DNS location info ( on dns-loc.mapper.ofdoom.com ), and with the disappearence of geourl, I decided to see how it would work as a replacement.
Even though geourl.org is back, I'm going to keep this site up, as I feel the service is too important to only have one site providing it.