If you have existing back problems (even if you don't, if you're 50+), many of the recommended exercises can do more harm than good. Take a look at the following video http://www.youtube.com/watch?v=U-K7jtcJ0Dc , and others from the author of Foundation, by Dr. Eric Goodman. Additional author is Peter Park, with forward by Lance Armstrong.

When most people think "core" they think "abs", and doing sit-ups, Pilates exercises, etc. There's a big difference between "core" and proper development of spinal support muscle systems. I've done several years of mat Pilates and yoga, and many of the poses put unnecessary strain on your back. They can be good if you don't have pre-existing problems, not not so good if you do.

Goodman and Park's system isn't new, and others have identified similar exercise regimens for back health. The information was just a lot harder to dig out before publication of Foundation. Having a mirror available really helps - as it does for other exercises like yoga, Pilates, free weights, cycling/spinning, etc. I'm getting a large, non-glass studio mirror for my new exercise room.

If you've seen a physio for your back, you probably have been doing some stretching and strengthening exercises. Foam rollers can be used to very good effect on tight muscles. Chiropractic may provide some relief, but I'm with Jethro that other options probably work better. If your insurance covers chiro, and you can find one that is recognized for competency dealing with back problems, give it a shot. I've been fortunate to have been under the care of an ortho and physio who have worked with Olympic and professional sports teams, and they're not keen on chiro for most problems. Personally, I'm a big fan of deep tissue, full body massages.