Esther of Yogatic has some nice, easy stretches and exercises that not only stretch out your back muscles and spine, but relieve any pain. She also has a wonderfully soothing voice and simple-to-follow instructions!
I happened to be at the beach yesterday (not recommended when your back is hurting, even after a chiro adjustment!), and did yoga stretching on the sand. I DO whole-heartedly recommend the following exercises, which all help to loosen up and strengthen your back: Eagle pose, Tree pose (also, the Palm Tree pose), Locust pose, Cobra pose, Crane pose, Dancer's pose (which can be done on hands & knees, as well) , Warrior III pose ("Balancing Stick"), Triangle pose, and Upward Plank pose.