The Telectroscope connects London and New York virtually. The installation near Tower Bridge is a great application of a giant webcam.

These real-time tele-presence installations are not new, but what is great about the Telectroscope is its size and its great Victorian era design. The story behind it is that there is a giant tunnel under the Atlantic connecting New York with London. The Telectroscope is an invention of Paul St George, a 53-year-old artist in based in London. You can use the Telectroscope for £1 and you will be able to wave into the earth and see New Yorkers waving back.
The Telectroscope is at the Fulton Ferry Landing by the Brooklyn Bridge in New York.
More details on the Telegraph.