Another great variation of the bench press is called the Off-Set Bench Press. It is called off-set as you will have 5-10 pounds more to one side. What this will result in is a massive recruitment of your core musculature, as your body attempts to stabilize the rotary force from the off-set of the weight. Technique is the same, but you must switch the off-set weight with each set to ensure even development. If you are performing this exercise correctly, I should be able to watch your core and shoulders and not be able to tell what side the extra weight is on.
The standing bar press is really a standing variation of single arm dumbbell press. Place an Olympic bar at the corner of the frame on a squat rack or against the wall and floor. When the bar is in the low position, it should be set so your hand is just at shoulder level, if you cannot get there, adjust the distance between you and the bar. Feet shoulder width apart, set your core, and press out to full extension. There should be no movement in your core, everything should be activated while your pecs, shoulder and triceps complete the movement. Check out this youtube video where I give a full coaching description of this variation.
Try out these variations, they will help your strength and the health of your shoulders!