Stewart recently showed me some very cool (and in some cases surprising) Flickr geotagging examples. Here's a few I loved.
Where is the neighborhood in Manhattan known as Tribeca?
Get your kicks, on Route 66
Food tour of Asia
What I love about the "tribeca" and "route 66" examples is that they show emergent knowledge in the system. Collectively, the efforts of many photographers map out a geographic element... Neat.