As a person who had an S5/L1 herniated disc, I did the following exercises as a part of my rehab after the laminectomy.

http://www.nismat.org/orthocor/progr...ackex.html#Ex1

It helped me a lot. I no longer get random back pain, only after a great deal of exertion (like after I put down 8 tons of stone for our patio).