Are you talking the acute irritability that comes while hungover, or just a general feeling that's difficult to pinpoint the cause of?
I still get roadrage like a motherfucker, and I still can be 'snappy' at times. I think that's part of being human in a society that sucks in many ways. I'm so tired of people's carelessness, and that's generally what will cause my anger issues to flare up. Skateboarding helps immensely for me, and I'd assume any exercise would yield a similar result. I've also been dabbling with some of the philosophies behind mindfullness. More specifically, letting shit go that I would otherwise allow to bother me. If I'm quick enough to catch it, I'll just ask myself "Is this worth being upset over? Is being upset over it going to make it any better?" and often times I realize that the only effect of being pissed about something that is out of my control is that I'm pissed, and that often just serves to alienate people. I don't know.