My favorite beginner sport is Rally-Obedience. It requires very little training, just that the human needs to learn the signs. The dog needs to be able to walk by your side, turn right, turn left, sit, stay, down. At higher levels the signs get more complicated. Novice level is all on leash, but after that it's all off leash.
ETA: There's also the "come front".
I know some people who have career rally dogs.
"And why do we fall, Bruce? So we can learn to pick ourselves up."