Has anyone made a shared online map of the last known GPS coordinates for the people who go missing?

Genuine question here: I am familiar with the most current map (paper version available for purchase from his website), but I am curious if anyone has ever started something like a shared map/wiki for people to update and add the last known coordinates? Even a simple google maps would work.

As an aside, I think it would be very interesting to note both the last known location as well as the location any body was found (if at all).

If this kind of thing is already started, I would love to get pointed in that direction.