I can also vouch for arnica. I've used it in gel and lotion form, as well as those little homeopathic sugar beads you hold in your mouth. If the injury is a large area, I tend to get better relief from the beads. Arnica seems to speed the healing process in any circumstance in which I've overused and abused my body.
Also, tiger balm feels good. Since the more you rub it in the better it works, it's also a great excuse to get a little healing human touch.
The stretch that I've found works the best for the lower back is to lay down on a carpeted or padded surface and pull one knee at a time toward your chest, holding for a while, then switching legs. If it's not too painful, you can also pull both knees to your chest and hold on to them, making your back arch, and rock back and forth like a rocking horse. I really like that last one for hip stiffness, but it's a bit too intense if you're really in pain.
Finally, you might try sitting on something that you can wiggle around on, like a big exercise ball.