The single arm dumbbell floor press is a great bench press alternative when you are lacking equipment or if you have any sort of shoulder issue. The floor limits your range of motion so you don't put undue strain on your shoulder, but you still get some great pec, front deltoid, and tricep work in. The single arm increase the core demands felt during the movement drastically.
How to: Grab a dumbbell with a neutral grip and lie flat on your back. Bend your knees and make sure to push your feet firmly into the ground. Raise the hand not holding the dumbbell straight up in the air and make a strong first to create tension throughout your body. Extend the arm holding the dumbbell straight up bringing the dumbbell off of the ground.
This exercise can be used as a part of an upper body or total body workout. This exercise is usually best served using a higher rep range since it is often hard to get real heavy weights off the ground for the first rep if you are alone.