Plenty! Once your dog has mastered the basics, the possiblities of where you can go next are almost endless. You can train your dog to be the most obedient companion, creating envy amongst neighbors and friends alike.
You may want to work with your dogs natural traits. For example, herding dogs make excellent flyball, agility and, not surprisingly, herder prospects. Flyball is a sport where your dog can run a relay to retrieve a ball ejected from a launcher. Agility is an obstacle course for dogs. Herding usually starts with ducks or geese and progresses to medium sized animals like goats and sheep. The dog can eventually learn to work cattle. Dogs from the hound family might be good at scent recognition where a dumbell is handled and then picked out of other dumbells. Retrievers can compete in field trials where lures are hidden and then retrieved. Don't limit yourself to your dogs natural traits as they may have hidden talents.
If the idea of competition is not in the cards, you can just train your dog in something and have fun at the same time!