GeoUrl is a nifty site that maps web sites to geographical locations, similar to geocoding. It also maintains this index in reverse, which you can use to find sites located near other sites in the real world.

To connect your web page to GeoUrl, follow their instructions to find your coordinates and add an ICBM header to your page. Then, ping GeoUrl with your site. Finally, add a link to other sites near your own, like so:

http://geourl.org/near/?p=http://snarfed.org/

The buttons page has a convenient GeoUrl icon: