The Tokyo Commuter Alarm Clock has dials for the major Tokyo rail lines. The clock is updated wirelessly in real-time with the position of trains on each line, so you know exactly how long you have to catch your subway.
(via OhGizmo)
Update: Russell sez, "The clock listed only gives the times for a single line–the Yamanote Line. This line loops around Tokyo with stations roughly two minutes apart. It does go through many major stations including Shinjuku, Tokyo, Akihabara, Ueno, Ikebukuro, and Shinagawa.
The Yamanote line is only one of many JR Lines (Japan Rail was privatized but previously run by the government). There are also many subways and private lines."
Update 2: Dan sez, "Unfortunately, it doesn't keep real-time information about where the trains are, it just syncs to a radio frequency clock signal broadcast in Japan to keep accurate time."
