If you planning on vacationing and riding in Europe, I recommend that you check-out BestBikingRoads.com.
It has over 400 roads and routes listed in Western Europe and Scandinavia. The roads are submitted by riders and include a map, description, and rating. It is a relatively new website, so the number of roads listed should continue to grow.
In order to submit a road or route, you must register as a member (registration is free). You can, however, view road information without registering.
The website is very professional and well laid out. It is worth a visit even if you are not planning a vacation or riding in Europe.