All you need for this one is some free wallspace.
Stand side on to the wall and imagine that your shoulder is at the centre of a clock face. Raise your arm up and place your hand on the wall in the 12 position. Then move through the hours, taking a few breaths at each position until you get to the 3 position. Turn your chest slightly away from the wall and feel how the front of your shoulder and chest opens. If you want to intensify the stretch, leave your hand in position and take a step forward.
Do you have your own favourite shoulder/chest openers? When do you use them?