This Microsoft Bing Maps SDK C# GPX Route Viewer code sample allows a GPX file to be read and to display its associated contents on a Bing map as a route. To use this code you must have the Bing Maps SDK, Windows 8 and Visual Studio 2012.
It's a little bit creepy, but it's also a little bit genius. Singles for Foursquare builds a dating and messaging service on top of the location-sharing application. The result is a mashup that could match up hip iPhone-using, Foursquare-playing, same-bar-going early adopters.
Wikimapia is a web service that allows users to edit information on a world map in a wiki format. Users of the site can add places, edit them, and get the information previous users have entered. The info there is currently pretty sparse, but the service is rather new. The company also recently released a Wikimapia API that supports getting information from the web service.