I came across this for the first time this evening. It's a new integrated map of the Tokyo rail network. it's seriously impressive. Not all stations are marked, but as far as I can tell, all lines are. (At least if the Toden Arakawa tram line and the Nippori Toneri liner are on it, I think all lines should be.)
It really gives a sense of the extent of the rail network.
This is the link to the JR East page.