Personality

I'm quite intrigued by the Myers-Briggs Type Indicator (MBTI) and David Keirsey's expansion on these ideas with his temperament theory. If you have any interest at all in this field, I'd recommend 2 books to start off with:

If you want a really easy to understand overview read People Patterns. If you want to go more in-depth, read Please Understand Me II. If you find yourself more interested after that, I'd recommend checking out Linda Behrens writings.

My MBTI/Keirsey type is INTJ (Mastermind), which is part of Keirsey's NT Rationals group. I first tested as INTJ back in a psychology class when I was in college during the 80s. I've taken a couple of "official" and a variety of different unofficial personality tests since then and I've always come up INTJ.

Here are more links to descriptions of the INTJ personality:

INTJ FAQs - dealing with INTJs, some humor
INTJ profile according to Life Explore
INTJ profile according to Type Logic
INTJ profile according to Personality Page