This project contains Visual Studio .NET 2.0 Classes that implement the Google Earth API version 2.1. These classes do not use the Google Earth COM libraries, but rather generate KML based on the documented API at http://earth.google.com/kml
QuakeMap GPS mapping program - see quakemap.com and download free trial there. This is a complete Open Source version (no different in features than the commercial version). You can compile it in Visual Studio 2008, enhance it to fit your needs.