One of my favorite dumbbell bench press variations is the 1-arm dumbbell bench press. I first came across this exercise when I attended a clinic with Wake Forest S&C Coach Ethan Reeve. Not only do you get all the benefits of the dumbbell bench press, but this variation works the anti-rotation function of the torso extremely well.
If you're looking for a new pressing variation, give this one a try!
Here is former Auburn University swimmer, and 2013 US Open 50 meter freestyle champion Karl Krug doing the 1-arm DB bench press as part of a hypertrophy-phase training session he is currerntly in.