Google Earth, Google Maps all graphical GPS systems are getting developed at Google, MV. This is just not enough. Google tools are user editable. Now I am talking about Google Map.
See the linkGoogleMapsMania. User can create the their maps on the GoogleMap. Add contents, images, draw Roads on it.etc. There are lot of map building tools measurement tools,image adding tool from flickre/picasaweb. You login into google and go here. You can edit the contents from Google Maps.