Pretty much everything the driver needs to know for speedy and safe journeys through France is available in real time, and even – sometimes – in English.
*Work in progress*
Vinci Autoroutes has a handy real time weather map matched up to the entire road network.
BisonFute is the national traffic website. Also has a handy jam calendar of the busiest days. Vinci publishes great animations of expected traffic flows – select the date you want then play for an hour-by-hour prediction of traffic levels.
All the motorway companies have their own traffic sites (see Vinci and Sanef) and twitter feeds (Vinci and Sanef). @TRAFvacances pulls all this together for holiday traffic but is (simple) French only.
Autoroutes.fr is the motorway operators’ association with a map of webcams (and another traffic hotspot map).