What a fantastic thread! Late to the party but simply had to add:
He explodes for no apparent reason, but somehow makes it your fault. At the end of the argument, you really end up believing that being 15 min late/spilling milk on the floor/forgetting to post his letter is totally unacceptable and makes you a bad, bad woman.
He takes you to a party as his date and then leaves to talk to somebody else for a very long time (sometimes hours). When he gets back, he acts as if nothing happened and if you try to express your disappointment he brands you as needy. Yet if you give him as much as a hint of wanting some time to yourself and your friends, he will never leave your side.
He knows how to push your buttons. So on one hand he will be terribly observant and treat you to things you have always dreamt of just to purposefully cause you pain the next minute. You'll think - how can he be so loving and then so cruel? But these are not two separate aspects of his personality, it is just his desire for control. He does not listen to you in order to get to know you as a person, he listens in order to exert control over you later on, which is easy to confuse with attentiveness.
Listen to what he says about himself and watch how others react to him. He is not generally liked, is he?
He believes the vast majority of people mean him harm. It is alarming when you consider the fact that most people tend to attribute their desires and motivations to others.
I have loads more, but many of them have already been mentioned!