Yahoo's Fire Eagle service is very much in its infancy, but we're already beginning to see some early developer applications pour out of the service. One of them, Wikinear is a smart mashup, combining Google Maps with Wikipedia. Every time you update your location on Fire Eagle, the map and related entries will change, which could be useful if you're traveling or feel like learning more about some of the buildings or attractions around you.
The site is optimized for mobile phones with simple text and links. While local services such as Yelp offer quite a bit more story telling and every day value for local attractions than even the largest Wikipedia entry, this is a fairly simple way of seeing an encyclopedic view of what's around you at any given time.
Note that you need to be a Fire Eagle private beta tester to use Wikinear, although if you've got Google Earth installed, you can get the same results by toggling the Wikipedia layer found in
Layers -> Geographic Web and navigating to wherever you are.