It's a great idea, Dale. I've envisioned similar things, but we just don't have the data on SITO to accurately place artists on a map of the globe. The first step would be to get the GPS coordinates of everyone's house (or neighborhood, or town, or state). Then we'd have to obtain a license to something like Google Maps to use as an interface.
I've most recently been thinking about these global-positioning topics for a video project I'm "working on".