Personally, I've never tried yoga, aside from the Child's Pose (shown in the list below) which really does a great job of stretching out the back.
What I do have though, is all of the muscle aches and posture issues listed below! "Sitting is the new smoking" (Wired Magazine) is a pretty scary thing to hear. It's important to get up and move around if possible throughout your work day. Go get a drink, take a brief walk during your lunch, stretch your limbs. On