I've been seeing many posts lately regarding anger and by extension, emotion in general. The main thing I've gotten from these discussions is that these emotions, especially the ones that touch on passion, like anger or desire, seem to be contrary to our Way. It seems to me, that the questions mostly revolve around how one is to reconcile these feelings with the non-attachment of Zen Buddhism. How to deal with it, in a sense. There are many answers to these questions, and they are very helpful, but I would like to put in my two cents. This is how I see the situation, through my current understanding of the dharma, limited though it is.
These emotions are strong, mainly because we have been used to expressing them for most of our lives. They are reinforced in our everyday interactions with others and in our past times, movies, competitions, all have an underlying ability to play on our emotions. We are taught that holding in our emotions leads to psychological issues and is unhealthy, so we express them. Buddha never told us to be stoics. He never advised us to be devoid of these emotions. We are born with them, they are as much a part of us as our hair color and our height. They are emotions that, as sentient beings, we have been gifted with to fully experience this world, and as such we should not seek to disassociate ourselves from them.
This is not to say that we should allow them to control us, for we are not hedonists either. No, our way is the Middle Way of acknowledgment and experience, and then acting from a place of clarity and balance. In this way, anger, love, are like tools. Take a shovel. It is inherently faithful to its original nature. It is a shovel when engaged in digging a well and a shovel when hanging in the shed. Use it too often and it becomes dull, its structure becomes weakened and it will break. Don't use it enough and it will dry out, splinter and rust away. Use it as appropriate, care for it and nurture it, and it will always be there, ready to do what it was intended to do.
So how do we deal with it? Usually the answer is “just sit.” And I believe that is the best answer. When we sit we gain many things, even though we have no thought of gaining and we do not sit in order to gain. We become patient, because we learn that this is a never ending process, and enlightenment is rarely (if ever) sudden. As we practice mindfulness to ensure that we are wholly here, completely now, that mindfulness and patience becomes the standard for how we live every day, and it gets applied to situations where emotion might other wise have overruled reason. In sitting, we come to a deeper understanding of ourselves and we let that self go, leaving nothing for these emotions to grasp hold of and direct. We understand that these emotions are what they are, and we understand that we do not have to be beholden to the karma generated by them and follow their existence with clouded action.
I think that the following koan is illustrative of that point, but again, this is just my view, and I hope it is taken with a liberal helping of salt.

There was an old woman in China who had supported a monk for over twenty years. She had built a little hut for him and fed him while he was meditating. Finally she wondered just what progress he had made in all this time.
To find out, she obtained the help of a girl rich in desire. “Go and embrace him,” she told her, “and then ask him suddenly: ‘What now?’”
The girl called upon the monk and without much ado caressed him, asking him what he was going to do about it.
“An old tree grows on a cold rock in winter,” replied the monk somewhat poetically. “Nowhere is there any warmth.”
The girl returned and related what he had said.
“To think I fed that fellow for twenty years!” exclaimed the old woman in anger. “He showed no consideration for your needs, no disposition to explain your condition. He need not have responded to passion, but at least he should have evidenced some compassion.”
She at once went to the hut of the monk and burned it down.