Child's Pose - When my lower back is in so much pain, I tend to get into Child's pose to relieve the pressure. I sit like this for 5 - 10 mins and it relieves the pain that radiates to my iliac crest/pelvis and to my mid-back.
Cobra Pose -sitting at my computer hunched over while working does me in. This pose, beginning from lying flat on my stomach to then pushing with my arms to arch my chest, shoulders, and neck creates just the release I need by stretching those overworked upper body muscles.
Cat Pose - This helps me stretch and mobilize stiff muscles throughout my neck, back and spine while engaging my hamstrings and core muscles.
I find I stand up after performing these poses and I have better balance, less pain, and a little bit more energy.