metro systems in France:

Lille | Lyon | Marseille | Paris | Rennes | Toulouse

tram systems in France:

Angers | Aubagne | Avignon | Besançon | Bordeaux | Brest | Caen | Clermont-Ferrand | Dijon | Grenoble | Le Havre | Le Mans | Lille | Lyon | Marseille | Montpellier | Mulhouse | Nancy | Nantes | Nice | Orléans | Paris | Reims | Rouen | Saint-Étienne | Strasbourg | Toulouse | Tours | Valenciennes

Systems under construction or planned are listed in Italics

Carto.metro - track maps of all French metro and tram systems

List of French trams at Wikipedia.fr

Ferrocarta includes lots of rail maps of France

FPTU - France Passion des Transport Urbains

MobiliCités - Le portail des transports publics et de la mobilité

Lineoz - Transport & Mobilité Urbaine (Forum)