Google Maps

Is an amazing thing. The resolution in many places has been gradually improving, and now has reached the point where I can spot my sister's car parked on her street. Nothing to download. You just start out with a Martian's view of the planet and zoom right in till you can see individual cows on a farm on a Danish island, cargo containers on a dock in Singapore, a baseball game underway in Philadelphia (they're shading the batter toward left field).