Try This Great Lower Back Stretch...
A) Get on the floor facing down resting on your knees and your forearms (not just your elbows), so your forearms and shins should be in contact with the floor.
B) Keeping your hips straight, lift one leg off the floor and straighten it, lifting it up until you start to feel the pressure on your lower back.
C) Hold it there for 10-20 seconds and then lower it and repeat the same movement on the other side.
D) Do this on either side two or three times, and repeat this three times per week.
This is a great stretching exercise for people who suffer from chronic lower back pain.