I believe in absolute morality, since I view the universe in a very purpose orientated sort of way. Moral things lead you to your purpose, immoral things lead you away (and possibly others as well). So I believe in relative morality as well. The morality of a situation depends on the person and on the situation. Heavy eating might be immoral for the average person, but it is fine for an athlete in training. Drinking might be immoral for an alcholic, but fine for the rest of us. etc.
This makes things tricky. Certainly if we had an omniscient and perfectly rational observer I believe that that observer could say whether each action a person does is moral, immoral or neither. But that doesn't do us a whole lot of good since none of us are omniscient or perfectly rational. So while each person has to be aware that morality for them may be different than morals of others, if we want to make any sort of meaningful society we have to set up a group of laws that apply to everyone. So we say "killing is immoral." Perhaps there is someone for who killing is a good thing (though I'm having trouble seeing how that could happen, I'm willing to allow the possibility). This does not mean that we should allow everyone to kill freely or condone murder, because for the vast majority of people it is immoral, and more importantly, it harms others and in a sense "is immoral to them."
Then there's the whole issue of our flawed reason. This is why it was far more important to condemning murder that it be harmful to others than it actually being an immoral act. Since we cannot even be sure of what is moral for us, we certainly cannot string up the morals of another person. So for things that don't harm anyone other than the actual person, there's no good reason to punish them, since we don't know whether this is actually good or not for them. But the second they start harming others we take action against them since our society is trying to promote the most good for all its members, and having those members be harmed is certainly not good for them. This does not mean that immoral acts are acts that cause others harm. It just means that practically and legally we should act like this is what immoral acts are.
As for my remark above that murder should be condemned because "for the vast majority of people it is immoral", if murder did not cause harm to others, I would not support legal or forcible action against it. I still would condemn it, and encourage others to condemn it, but this is to help those who may be considering it. In all likelihood it is an immoral act for them, so they should avoid it, this is what condemnation of certain acts is for.
So yes absolute morals relative to person and situation, but practically we should act like immoral actions are "actions that harm another."