Keith Gessen has an interesting article about Moscow’s horrible traffic, Letter from Moscow, “Stuck,” in The New Yorker (August 2, 2010, p. 24).
Among other things, he describes Yandex Probki (Яндекс.Карты), an excellent example of a user-created map, which shows Moscow traffic patterns in real time. The site’s content comes, not from webcams or pavement sensors, neither of which would both practical there, but from GPS-enabled smartphones. Users send in descriptions from their own situations.
You can get a sense of the site from this video below, but you can also explore the map itself and get a sense of the enormity of the traffic jams, even if you don’t read Russian.