One thing we did with my DD(now)7 was hand her a piece of paper (or several, depending on the intensity) and tell her to tear it up into the smallest pieces she could. It gave the feeling of destroying something which relieved the anger and frustration; it redirected her focus to something other than what she was really mad about; and we were usually able to laugh about it later when we used the confetti for an art project.
Trying to redirect her anger and frustration into something slightly different, but more acceptable usually works well and helped our DD start to figure out her own ways to direct her frustration or anger - rather than suppress it. Screaming is generally not OK, but going to your room and burying your face in your pillow pretty much makes screaming OK and don't we all feel like doing that sometimes? We might redirect stomping feet and huffing into marching or running 5 laps around the house - maybe even timing it to make it a race.
Hope those ideas help at least a little.
