I have an idea I think would be cool, and fairly useful, but I have no idea how it would work.
Have a map of the world, large enough to make out most of the countries, etc. We have the red markers for each member, at this "world view" some of them would probably really run together. Then you can click anywhere on the map to zoom in to a view of just the country, or maybe continent. Same thing, all the red markers, now you would see a bit more detail. The North America map would show state lines as well to help out there. Finally, one step farther, for the U.S. anyway, a user could click on a individual state, or maybe region of states, and get a full view of that, at which point nearly every red marker should be spaced apart enough to signify each member it represents. While not getting SO detailed as to tip off the exact location. SVXes are rare, but any theif or other devious character looking for one probably already knows there is at least one in every area the map would show. Narrowing location down to a city isn't revealing too much.
As far as getting information on the map, it might be best to let each individual member enter that themselves somehow. Have it linked in with their personal profile, and similar to a poll, they can only put one mark on the map (we wouldn't care about multi SVXes, so much as the member themselves).
Okay, there is my cool idea that I have no idea how to implement.