There are lots of recommended stretching and exercising programs. Some are mutually exclusive, such as flexion stretches vs extension stretches. You will likely hear many repeated claims of this or that magic stretching program that reversed person X's chronic back pain. Keep in mind that back pain tends to go away with time, so the real cause may not be the stretching. Also consider that there are multiple causes of back pain, and one program of stretching and exercise is unlikely to be right for all sufferers. That said, keeping limber and fit will no doubt help your problems, as long as you don't overdo it. Studies have found that doing physical therapy can actually be worse than just maintaining a relatively active life following a back injury. The implication is that people are overdoing the exercise, and actually exacerbating the problem, whereas with normal activity such as walking this is less likely to happen. In my life, I've found that I tend to have more periods that are relatively pain free when I elect to keep my special exercises to a minimum, and just go on a lot of long walks. I suspect that an active life combined with a very careful regimen of stretching would be even better for me, but empirical evidence suggests that I haven't found the proper conservative level of stretching and back specific exercises that is safe for me.
With that fairly lengthy disclaimer and warning, here is a some links to exercises for lower back pain. Don't overdo them, but do give them a try.
Traditional back pain stretches - this is what you would likely see on one of those photocopied handouts your dr would give you the first time you come in complaining of back pain.
(more to be added).
