EarthView 

EarthView is a dynamic desktop wallpaper and screen saver, which displays beautiful views of the earth with daylight and night shadows. It produces colorful, high quality, high resolution images for every screen resolution - even beyond 1600x1200!
wallpaper screen saver screen saver earth planet city night day clouds atmosphere weather world globe

EarthDesk 

EarthDesk replaces your static wallpaper with a high-resolution rendered image of Earth showing current sun, moon and city illumination as well as real-time cloud coverage. Many different options are available for configuring the map image.
earthdesk wallpaper world map time desktop screensaver screen saver