+100 to the having kids comment. Preface any thoughts when you are angry and about to do something wrong by thinking about whether or not you want to be around for your kid(s).
One thing I don't get is a lot of the posts here from folks that start off "I'm an easy going guy but.." A temper is a temper, whether you repress it until something blows up (trivial or not) or you lose your bearing in otherwise stressful situations.
When you feel like really going off on someone - practice taking a just 2-3 seconds before speaking, being deliberate but firm in your communication. There just are very few things in this world that are worth really going off on someone -but in all cases, losing your cool equates to losing your argument and your position of empowerment. It takes a strong man to conduct restraint rather than one who acts totally on impulse.