If you are looking for something different for the back muscles, consider the alternating pullover exercise. The largest muscle in the back is scientifically known as the latissimus dorsi. You might see it referred to as the "lats" or "wings." The lats are used any time you pull something. For example, when you open a fridge or a car door, you are primarily using your lat muscles. Here is how this exercise is done:
Begin by lying down on a stability ball. Position the ball on your upper back. With dumbbells in each hand, extend both arms directly over your head (Note: The elbows can be slightly bent, but they must stay locked into position). Slowly lower one dumbbell backward until it is parallel to the floor. The dumbbell in the opposite hand should be lowered forward toward the thigh. Perform the movement of both arms simultaneously in repeated fashion.
Position ball on upper back. Keep elbows locked. Simultaneously extend one arm forward and the other backward.
Repeat the exercise several times.