Mini Tokyo 3D is a cool draggable web map which shows most of the main train lines and train stations in Tokyo.
You can drag the map around in a web page and click each station to get more info about it.
Some stations have live webcam buttons you can press to see a live video feed of the area.
You can even see where trains are, where they are going, their numbers, and times.
If you have a mouse with scroll wheel, or a touch-sensitive mouse or trackpad you can zoom the map in and out by swiping with your finger.
Very cool.