Millions of Photos Put in Place
Now that some cameras have built-in GPS radios that automatically capture data about where exactly a photo was taken, you can use one in conjunction with Google Earth and other tools to start building an entire world full of images.
Google Earth incorporates several different ways to explore traditional "ground level" photographs of the world. But the folks at Metal Toad Media have taken the entire catalog of the Flickr photo-sharing site and implemented it as a Google Earth-compatible feed. You can see user-uploaded images of the Grand Canyon, for instance, that will have you virtually standing on the edge of a precipice. In August, Flickr boasted an incredible "3.2 million things geotagged this month," so adding its content to Google Earth brings a vast assortment of images from areas you might wish to explore.