Hammacher Schlemmer has this useful device named exactly after its main function: the Back Stretching Pain Reliever. What it does to your back while lying is to support your spine’s natural curvature in order to relieve any back pain. The device comes in a compact form factor, which makes it easy to use anywhere you are, and store in tight spaces.
The device features 15 ABS molded ribs, each forming two nodes that align with muscles of your mid and lower back without causing pressure. As your body weight presses the nodes, the fatigues muscles relax.
Find it at Hammacher Schlemmer at $39.95.