A system of animating the window lights of buildings. The first iteration was made in 2001, and had animations and an interactive low-res version of Pong.
The latest version from 2008 was considerably more advanced:
They’ve released free software and Processing libraries to create content for the system: http://blinkenlights.net/stereoscope/create. The hardware was built on wireless 2.4ghz dimmers, all based on open standards here: http://www.openbeacon.org/.