If you have Google Earth, you can now see Encyclopedia of Earth articles as you navigate the planet:

http://www.eoearth.org/eoe.kml

The backend code is pretty crude, but I believe that I have things serving up “streaming” KML data the way that Google Earth expects it.

Geonames has all sorts of geocoding data available via a fairly extensive web services interface (in both JSON and XML!). Their data is also available for download, with a Creative Commons license.

• Determine country and (often) state/province given a latitude/longitude
• Find Wikipedia articles near a point or within a bounding box