Hey Slayer, I've been thinking and researching and so wanted to recommend a change to the "lying buttocks stretch" which I think is much better...and to anyone else I've recommended this to (Matt, Phil?)
First of all even though it's called the butt stretch you not really stretching the glutes. Just so everyone knows there is no need to actually stretch the gluteus maximus. Anybody ever got tight in that area? I doubt it. It's not a muslce that tends to shorten. So what you're really trying to stretch is the piriformis which runds deep through the glutes. This can become tight as it becomes stronger.....on the other hand certain chronic habits can make it weaker and tighter at the same time. You could also just say it's a hip stretch.
Anyway to make a long story short I wasn't satisfied with that stretch so these are the ones I'm doing which I like better:
To do the piriformis stretch, lie on your back, and flex the right hip and knee. Now, while grasping the right knee with your left hand, pull the knee towards your left shoulder. This adducts and flexes the hip. In this position, grasp just above the right ankle with the right hand, and rotate the ankle outwards. This applies internal rotation to the hip and completes the stretch. Another way to do this stretch is to stand on your left foot and place the right foot on a chair, such that the right knee and hip are flexed at about 90 degrees. Now, using the right hand, press the right knee across towards the left side of the body while keeping the ball of the right foot on the same spot on the chair.
There are other ways but these are fine and more efficient I think. As such I would do it for a shorter time and build on it. And remember the goal is to keep the muscle loose with a normal range of motion not to stretch them to the ends of the earth.
Keep in mind that the other is still a good stretch and the piriformis would be a seondary stretched in that. This new one is just more a primary p stretch and that muscle is one likely to cause problems. I could recommend a couple of variations to the original stretch which are all just variations on a theme.