Sorry to appear persistant, but I've just found this site:-
http://florent.brisou.pagesperso-orange.fr/Lignes.htm
You can click on a region (Nord, Est, Sud-Ouest etc), and a list of all lines within that region - clicking on a line will give you a map of that line, complete with all stations and junctions etc. There's also an alphabetical index to all stations in the top left-hand corner. All very useful - I wish I was going to France!