I mentioned about this in another thread, but thought it would be appropriate here as well. I am in the midst of creating a program I call Clearwave that uses interpolation to generate a kml file for Google Earth. I would bypass the whole Google Earth part, but I don't know of any free API's out there for C++ that allow for connections to satellite imagery servers. It is created in C++ and takes roughly a minute to interpolate the area of a very large parking lot on my machine. You may ask, "How is this different that what other people have?" See for yourself:
http://www.bitcorruption.com/clearwave1.jpg
http://www.bitcorruption.com/clearwave2.jpg
http://www.bitcorruption.com/alerus1.jpg
The program parses Netstumbler data and then creates an overlay for Google Earth so you can see the "actual" signal coverage. I'm trying hard to get it done as soon as possible. Right now it supports analysis of 1 AP but will support multiple AP selection after debugging. Does anyone have any netstumbler files that focus on sampling the area around a specific AP so I can test/debug?