APOD (Astronomy Picture of the Day) downloads an astronomy pictures every day, and sets it as desktop wallpaper. The image includes a detailed description written by professional astronomers, that can be shown and hidden when you click on the small link. The program runs in the system tray and also includes link to the NASA picture archive, from where you can browse previous APOD images, as well as an option to print the current image. Nice, interactive desktop enhancement for astronomy fans.
