I don't know if you know, but I'm a big Mac guy. Yup. So, I was reading TUAW (The Unofficial Apple Weblog) and they posted about this desktop app called OSXplanet. It's sorta like a geochron (wikipedia it if you don't know what it is). I takes the world and slap on your computer. It shows where the sun is currently shining and where its not, it was that cool night light thing around the cities. It can also show clouds, satellites, storms, earthquakes, and volcanoes. In short, it's frickin sweet. It doesn't stop at planet Earth either. It can also display the Moon, Sun, and all the other planets, including the now dwarf-planet Pluto. If your running the marvelous OS X, then head over to the OSXplanet site and have a looksy.
Also, if your into astronomy and planets and stuff, check out Stellarium, a badass app for all platforms, that puts the cosmos on you're computer, and Celestia another cross-platform planetarium app.