Every once in a while, someone comes up with a simple but really great idea that legitimately improves the way people use their computers or gadgets. Photo geotagging—encoding photographs with map coordinates—is one of them. Paired with a program such as iPhoto, you can suddenly see all of your photos on a map of the world, and jump from location to location to see what you did there. More broadly, web-based photo-sharing services can…
