Death by Bodyweight
30 Days Without Weights (parts 1-3)
Homegrown Muscle (on Men's Health)
Turbulence Training
All can be done at home.
If you're looking for something to do in a park, you can do use the bars to do pullups, chin ups, dips, and hanging knee/leg raises. Also, use benches to do step-ups. Obviously you can do planks, pushups, prisoner squats, and lunges with no equipment. Another alternative leg exercise would be a bulgarian split squat, which could also be done using the bench.
That said, what are your goals? You should consider adapting a weight training routine rather than just running and body weight exercises.