Google Earth
I just discovered Google Earth, which was recently released for the mac. Sure we've all played the "look at a satalite view of your house" game, but this is an impressive application. I saw the Pyramids of Egypt, the Eiffel Tower, the Sydney Opera House and 1 Infinite Loop (the headquarters of Apple) for the first time. Actually it's interesting how the Pyramids are (what looks like) scarecely a mile from a huge green park and tons of urban development. To the southwest is barren desert (probably protected) to the Northeast it looks like any huge metropolis. Funny how the national geographic shots of the pyramids never show you the city buildings on the skyline. Although most locations are quite fuzzy, several metropolitan landmarks are quite clear. But the best part of the experience is watching the camera rise up and down in an eliptical path as you zoom from one part of the earth to another. Privacy issues aside, it's a lot of fun to play with.