This installation by Troika (its Troy-ka not Tro-kia, anyway) is again located in Heathrow Terminal 5 and was built using large EL or ElectroLuminescent display technology, Troika have created a typeface and display whcih show the time in various places around the world, the idea is to link the location with far away places.
Again I like this because of its use of light in interesting ways, and its large scale.