Lately, I've seen in a few places where people have said anger is an unhealthy or negative emotion. I care to disagree.
Anger is, like every human emotion, healthy. But I do make a distinction. For me, there are two forms of anger. The first I call righteous anger. This is when someone has done an injustice upon you; and I'm using "you" in its broadest sense. It can apply to nations. Say what you want about nationalism, the anger felt by us Americans after 9-11 was normal and healthy. It'd be inhuman to not feel angry, and I doubt even Jesus, the Buddha, or Lao Tzu would be so heartless. Anger is the fire that drives action towards justice. Very useful.
Then there is when things don't go your way, when people don't do what you want them to or don't live up to your expectations. This is ego-anger. The anger of the little king or queen we all feel ourselves to be not having the world bow down to their whims. This some might call unhealthy, and maybe it is (but I think it's really the ego that's unhealthy).
In fact, I'm kind of tired of people denigrating sadness too. It's normal to feel that way at times. I heard a while back they were adding grief to the DSM IV, the Diagnostic and Statistical Manual of mental disorders, the Holy Bible of psychiatry. I was majoring in psychology before I quit school, and hearing shit like that makes me glad I got out of the field. As if there's a time limit on what constitutes healthy grieving a dead child, and after that you're sick. Sadness in it's basic sense is normal too. People aren't cheery all the damn time, and telling them their sick for being down in the dumps is itself sick and wrong.
The real issue is what we do with these emotions. Bottling it up, supressing it, this is not healthy; expressing the emotion is obviously better. Yet what's unhealthy about anger is usually the way it is expressed. The expression is the release, the way through it; ignoring it isn't going to work, nor is drugging it away. The nuance is this: you have every right to be angry, even to be hateful; you do not have a right to hit your spouse or kick your dog, and you do not have the right to strap on dynamite and blow up a bus.
It gets tricky, though. How do you safely express your anger when your boss does something stupid that is going to cost you hours of tedium? Do you bury the feeling and keep your job, or tell him what you really think? Part of the solution might be to express, somehow, the emotion in the very moment it rises. Let it rush in, and out, like a passing storm. Or maybe expression in the exact moment isn't necessary; but get it out soon. I find anger and exercise go together great: do some push ups, or run a mile or two. Anger is energy. Hold it too long and it turns to hate.
As for sadness, crying is fine, or listening to sad music, writing a poem or journal, or whatever works for you. I think Freud called this sublimation, the turning a "negative" emotion into some kind of positive. I guess depression is sort of the negetive side of sadness, that of dwelling too long on it, from not expressing it and letting it go. Like hate, it is a trap. We have the right to feel these ways, but they aren't good for us and are the sign of neglected emotions.
I do know one thing. Psychology/psychiatry should be focusing not on pathologizing these natural emotions, but on helping us deal with them in productive ways.