Traditionally, I’ve never had the same wallpaper on any computer for more than a half hour at a time. I like my wallpapers to rotate, since I’m surrounded by 3-4 computers at any given time and usually only working on 1 or 2 of them. This way I can have nice pictures flying by to keep my perhipheral vision entertained and people walking past my window can marvel at the 3D art I have displayed.
The OpenStreetMap (OSM) project is well on its way to producing a free, user-editable street-level vector map of the world. OpenAerialMap (OAM) is similar in scope, committed to building a free, bird's-eye photographic map of the world. But it faces a unique set of challenges.