The dog park is a wonderful place to practice training. If you recall your dog for short training sessions every couple of minutes, then tell them to go play again, you are using the other dogs as both a powerful distraction and reward.
One of Pierre's agility trials. He was a great dog and is greatly missed. When I first pulled him out of the shelter we all thought he was not going to do much. In the end he became an awesome dog, an important part of the training team (helping with assessments, training puppies and rehabilitating dogs). Dogs like Pierre only come around once in a life time. And I have been blessed to have shared my time with a few of these wonders.