Well, Ludwig dvd (rental) is on its way to me at this moment from Lovefilm! I think Renoir could be credited as the real fore-runner of Italian neo-realism; his film Toni is clearly a major influence on the movement (even if you weren't aware of that, you'd inevitably think "Neo-realism!" when watching it), especially on early Visconti, and of course Visconti was his assistant in the mid-30's, influenced by Renoir politically too. There's a current running from Toni, Ossessione, through Voyage to Italy to Contempt about couples' troubled relationships (more passionate in the first two, existential in Voyage to Italy as wpqx says, and then more coolly intellectual and cynical in Godard). Still some strong links generally between French + Italian cinema, including some financial co-funding, exchange of settings, actors, in the early 60's.