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Drumsticks
Even if you do not have your own drum set, pounding drum sticks into a pillow can be incredibly therapeutic.
Bongos
If you prefer pounding on something that makes noise, bongos are ideal. They are small, provide a nice workout for your hands and wrists and sound pretty cool too.
Books
The Squeaky Wheel: Complaining the Right Way to Get Results, Improve Your Relationships, and Enhance Self-Esteem, Dr. Guy Winch.