This is perhaps the coolest new piece of technology I have seen all year. Google has just expanded their Google Maps service to allow for full 3D navigation of cities. Currently it is limited to a small number of large US cities like New York and San Fran, but presumably this will be expanded in the near future. Check it out by going to Google Maps. Then select 'street view' and zoom in on on say New York city or San Francisco. You'll then have a little man icon that you can drag to different parts of the map. When you do this a window will pop up with an interactive 3D view from the point of view of the man. I can't imagine the labour that went into accumulating all this data, but boy is this cool.
Addendum: I wonder how long it will take for Google to merge this data with Google Earth, allowing for 3D navigation of the Earth all the way down to the street level.