Once outside of Paris, restaurants are plentiful, but Internet guides are scarce. The traveler will be best served by picking up a copy of the latest Michelin guide or Gault et Millaut, both highly reputable and exhaustive. Still, if one wishes to do some preliminary research through the internet, Emroll Net offers a directory by region and Yahoo organizes its listing by départements.
The local press may be a good tool as well. Try the regional French press, prepared by the daily Ouest France. But if you find the information too limiting and are looking for a friendly neigborhood bistro or auberge (inn), the information you will gather on the spot from concierges, landlords, shopkeepers or passers-by, may serve as the best documented, if not necessarily the most trustworthy, recommendation you will obtain.
