Earth 3D for Mac is on sale for a buck (thanks to John Kheit for the heads up). It’s a gorgeous app—if you have a solid video card—that shows you our planet. It includes thousands of geographic features, more than 500 wonders, a day/night view, a screensaver mode, support for multi-monitors, and it’s just amazing. As I mentioned, you need a good video card for it to work, but at a $1, it’s worth the risk if you aren’t sure (or are getting a new Mac!). It has a 4.5 Star rating on the App Store.