Do what I do: write all kind of crap in chat, it helps... a little. Having a bed nearby is great as well so you can punch something soft and don't screw up your hand.
But now, seriously, the moments I don't rage like a maniac are those when I have made many profitable things away from the computer - it's like I enjoy the session a lot more. When I play all day long, I end up getting mad every minute.