This is an older thread, but a quite helpful one, so I decided to dust it off.
Primal screaming into pillows, in your car when away from crowded spaces and with the windows rolled up, in the woods on private land, and at home alone works wonders for me.
Keeping a hammer and some nails handy and some scrap boards to pound them into can come in handy, too.
I used to smash beer caps with a hammer to make percussion instruments, and that was quite therapeutic, too.
Shaking my body, kind of like a dog does, helps release energy, too. Sounds and feels quite silly at first, but really does feel good, based solely on my experience.
Chopping wood can let out some steam, too.
Running like a fool while hanging onto the safety bar of the mini-trampoline and singing or screaming at the top of my lungs has been super beneficial, too.
I'm always a bit envious of children in this regard. They can have their tantrums and emotional outbursts whenever and wherever and no one thinks twice about it. lol