Personally, I think "graphology" is like palm reading. Apart from matching handwriting samples to support statements that a certain person wrote a certain document, I don't think there is much sense studying handwriting. There is simply no proof that there is a massive pool of unconscious energy in everyone, trying to get out, and expressing itself in things like handwriting. It's all sort of a Freudian idea, and Freud's entire theory was based on his own ideas--backed up with no proof--that he believed were self-validating ideas ("it is because it is"). Graphology also assumes that all people are alike. i.e. that aggression will look the same in all people, etc. Who says a dash at a certain angle means a certain thing?

Concepts like graphology gain a lot of attention and support because people have a natural tendency to identify with vague descriptions. Horoscopes work on the same principal. If I tell you "you're a thoughtful person, but if you don't apply yourself today, you could misstep" you'll probably agree that "yeah, I'm a thoughtful person!" (who wants to think they don't think enough?) and my prediction is so vague it could apply to anyone. When my prediction "comes true" my magical abilities seem credible. After enough repetition, you may become a believer in my great horoscopes.

We all have a certain desire, I think, to know ourselves better, and so when there are simple "tests" that give us an answer, it's tempting to believe they're true. Especially when they're a bit flattering, as they usually are. But if introspection were really that simple, I think we'd have to concede to being simple, shallow cognitive creatures. Are we? I'd like to think not.