Exercise 1: On hands and knees, breathe in, expanding pelvic region. On out breath, draw belly button back towards spine while raising right hand forward. Reverse and do with left hand raised out. Six times on each side, twice a day.
Exercise 2: On hands and knees, move your spine in a wave - on out breath, point tailbone down and continue movement up through the neck. On in breath, do the same in reverse (easier to describe this one in person). Six times on each side, twice a day.
Exercise 3: (this one feels awesome), one hands and knees, is more comfortable to keep the wrist taking the pressure into a fist position rather than flat on the floor. Keep left hand on the floor, and thread your right hand between your arm and knee, twist as far as is comfortable (I can feel this from the base of my spine up through my neck). Do the same in reverse. Six times on each side, twice a day.
Exercise 4: This one sucks and really hurts. Lay on your left side, rest your left arm out on the floor above your head and rest your right hand on the floor in front of you. With your legs slightly bent so your feet and back are aligned, raise your right knee towards the sky but keep your ankles/feet together so you're opening up your legs like a clamshell. Don't let yourself roll backwards, do this up against a wall if possible. 10x on each side, twice a day.
Exercise 5: On hands and knees, like exercise 1 but when you are raising your right hand forward, you are lifting your left leg backwards, keeping your back flat.
When finished, sit in a chair and with your left leg bent, put your right ankle up on your left knee (like if you are trying to sit cross-legged but can't quite make it) and lean forward into a stretch. Then do this on the other side.
Lastly, and I've heard everyone should be doing these - wall pelvic tilts. They feel really good and are also good for sciatica. Stand up against a wall with your feet planted on the floor in front of you a foot-length away from the wall. Curl your tailbone under and tilt it upwards, and this should press your lower back into the wall. Hold for 5-10 seconds, then release. Repeat 10x, twice a day. This also helps pelvic floor muscles.