Some assistant exercises for the upper back I use a lot (other than deadlifts, chins/pull-ups, snatches and cleans).
Shoulder press in squat position, behind neck
With a barbell on your back, sit down in a squat, then press up the barbell (behind your neck) and stand up. Very good for mobility.
Circus act? Na, I like these, first saw them demonstrated by the russain weightlifter Dimitry Klokov. Works the shoulders and upper back. Also good for mobility. Fun!
Strength and body building exercise for the upper back. It’s common that people tend to stand more and more erect for every rep. To keep your posture you can let your forehead rest on a bench or racked barbell.
Cable rows, wide grip
I don’t like fixed machines, but cable pulleys are ok. I mainly use a cable cross for most of the “machine work”. Cable rows with a wide grip is one of my favorite row exercises for the upper back.
Body weight exercise for the upper back. Should definitely be up there with chins and pull-ups as a standard body weight exercise for the back. Multiple grips can be used; wide, narrow, neutral, pronated and supinated.