Man, oh man, I can see the jokes flying left and right... !!!
In addition to the above mentioned stretches, I've got two stretches that may work for you - one from my days as a sprinter and the second from Bloodybirds. For the sake of simplicity, I'll use the right side for the stretch...
1. Find a place that has some sort of a step at least 12" or higher. Raise your leg and place your right foot on top of the step and keep your left leg on the ground. Keep your head up, shoulders back and back straight. Now, slide your left foot and leg back behind you and shift your weight onto your right leg - MAKE SURE YOUR KNEE GOES STRAIGHT OVER YOUR TOE!!! As you shift your weight forward, try and "sink" into the center of the stretch by making your right thigh parallel or slitghtly below parallel with the ground and your left leg fully extended behind you. If you have done this properly, it will look like you are doing lunges and your glutes will be stretched where they tie into your hamstrings. Hold for 15-30 seconds and repeat on the other side. Do this at least twice per leg.
2. Begin by sitting on the floor as if you were about to perform the "butterfly" stretch - on your butt, feet together and drawn into the groin. Extend your left leg out in front of you and rotate it around and behind you. Your right leg will not have changed its position!!! Your left leg is now behind you with the top of your left thigh in contact with the floor as well as your knee and the top of your left foot. Slowly press down on your right leg and try to place the outside of your right leg on the floor. Slowly bend forward at the waist and gently begin putting your chest on your right leg. If you have done this properly, it will look like you are laying down on your right thigh with your left leg behind you. You should feel a stretch more on the "meat" and/or the outside of the back of the leg. Hold for 15-30 seconds and repeat on the other side. Do this at least twice per leg.
Hopefully these will help...