One thing that I've found lately is that I don't usually do much to actually calm myself, because my emotional stability is usually pretty stable to the point where people think it's odd that I don't get angry almost ever; I find that what I do most often is sober my thoughts. This may sound...
One thing about me is that I don't show anger that well, so people don't really know when I'm angry, so they don't understand why I go off and vent.
But usually I listen to music, and rest, or just meditate.