Lifehacker pointed me towards a fun program called Desktop Earth. It dynamically changes your desktop wallpaper with a picture of the Earth from space at that moment, combining the wonderful Blue Marble: Next images with City Lights. You can download the latest cloud data (right click on the icon for this option, as it’s not in the main preferences panel). I’ve set mine to update every five minutes. Very cool.
Don’t know how impressed my relatives in Australia will be, mind 🙂 You can set it to display the full globe, with black bars at the top and bottom. My desktop is unusually tidy because of the recent reinstall, btw.