I had been looking quite a while for an online English map of Tokyo, and I bumped into one at last. OpenStreetMap is a free editable map of the whole world, a Wiki world map, to say it short.
Though it doesn't cover the smallest roadway, it is detailed enough for it to be useful in searching your way through Tokyo. The best thing is that the map is in English !
I'll need more research to see whether we can use this map instead of GoogleMaps (which is in Japanese) to layout our ride courses and incorporate the maps into our site.