I'll do my best to describe my favorite neck/back stretch

You get on your hands and knees, your legs slightly apart, and your back and head straight and flat. Then you lift one leg straight out behind you and at the same time raise your neck and eyes to look up at the ceiling and hold for just a count or two. Then pull that same knee in while lowering your eyes and bending your neck so that your knee almost touches your nose (your leg is still off the ground). Then do the other side. If you want to add some arm work, after your stretch your leg out back you bend your elbows once and then straighten, like you are doing a push up, before bending your knee back in.