As a cartographer / cartophile you need something on your computer desktop that screams “Maps!” Technically, Desktop Earth isn’t it since it is a compilation of remote sensing images but this will be the closest you come. Download a wallpaper generator that will display an image of the earth on your desktop according to the time of day and year. The download file is a hefty 34 MB and expands to 110 MB once installed. This only runs on Windows so Linux and Mac users will have to content themselves with an image generated from a web-interface.

By way of La Cartoteca and Very Spatial.