There is no list because there are just too many and way too many different organizers to get their information all in one place.

Each area has good sources for events in their respective areas. I would suggest posting on the regional forums for the areas you are interested in traveling to.

Also - "fun" means something completely different to many people. To me fun is something longer, higher, faster than any other ride around. To some fun is the shortest, easiest route with the tons of gut growing food.

Pick your poison.