Myers-Briggs Test
Actually, now that I read some of the descriptions (another) of this personality type, I tend to think that it's exactly what I am. :) It almost fits me to a T.
INTJ
Introverted Intuitive Thinking Judging
Strength of the preferences %
56 88 38 11
moderately expressed introvert
very expressed intuitive personality
moderately expressed thinking personality
slightly expressed judging personality