GeoURL
I like this one: GeoURL (via Howard Rheingold, Smart Mobs). You add two <meta> tags to your HTML – one with your latitude and longitude coordinates, and one with the name of your weblog (here’s how). You then ping them, and soon your weblog will be indexed, so that you can see which weblogs are geographically near yours. Here are my neighbors (within a 500 mile radius).
By the way: I used Maporama.com to look up my coordinates. According to GeoURL, I live one mile west of the center of Stockholm. You get an RSS feed with the neighboring weblogs as items. Here is a list of all sites near Stockholm.