M.S.
I also have an 8 year old son who has had episodes of temper tantrums and other expressions of anger since he was very young. On the advice of a good friend, we started counseling when he was about 5 or 6 years old. It was a great experience for me to learn about communication and some parenting tools to deal with his behavior. When he is expressing his anger in a non-socially acceptable way (eg. fits of rage, temper tantrum, etc.), he was sent to his room if we were home or into time out if we were outside of the home. He stayed there until he was able to calm down. Once he was able to calm down he first needed to apologize for his behavior and then we would talk about why he was angry and how he could have expressed it differently, or handled it differently in a socially exceptable way (eg. "Mom I'm really angry because... Can you do this to help me..."). The basic lesson is... it's okay to get angry or to be angry, but it is NOT okay to handle it with a fit of rage or temper tantrum, etc. This has worked really well for us - he has learned to manage his anger. I can't remember when he has had his last problem with anger.