One of my good friend's mom (who is big into yoga, stretching etc.) was showing me some stretches. I told her I wanted to know some stretches to loosen up my lower back. She then taught me my now favorite stretch ever.
1) With straight, locked legs, bend down into a classical ham stretch (touch your toes), and let your torso hang for 10 seconds or so, and stay completely relaxed.
2) Then, take your hands and clasp them behind your head, and apply pressure on the back or your head, like you are stretching your neck. The result is a stretching sensation thru my calves, hams, low back and erectors and neck. It's awesome.
Plus, she showed me some hip stretches I already knew about. Now that I am getting up in limit strength, I understand the importance of flexibility, recovery and muscle balance in order to lift heavy for a long time. Hope you do too.