some links:
http://www.golfonline.com/golfonline...484811,00.html
and pilates:
http://exercise.about.com/cs/abs/l/blyogapilates.htm

I have a back problem, too. My tips for flexibility and stretching are:
1) Do stretching 2 times every day - not much, just to get the stiffness away. You can do passive stretching with duration from 30 seconds to 2 minutes per muscle/movement or active stretching -> just use your own muscles and do a stretch as tight as you can - with out extra help - like gravity. (Bumping movements are not recommended.)

2) Just before a game - start from your legs and go up to your neck. Lower back has lot of joints and muscles and core is connected a long way. Find your stiff areas by doing your swing on "slow motion", but big as possible. When you feel a tight muscle - stretch it - actively or passively.

3) Find some "check up" movements. I do "hagging the sky" and "arm rotation" that I learn in martial arts. I do the movements every morning and some Tai Chi, too.

Stretching is like finding a swing - you can copy movements from others, but you have to feel what is good for you. My two cents are: Stretch tow times everyday - at least the muscles that need it the most.

Hannu