One of the most used personality assessments available is the Myers-Briggs Type Indicator (MBTI). It basically measures people in four areas- relation to others (introversion/extraversion), how they process information (intuitive/sensing), decision making (thinking/feeling), and how they order their lives (judging/perceiving).
Here is a website that describes the MBTI very succinctly: Myers-Briggs Introduction
The full MBTI takes about 2 hours to complete and has about 500 questions. I took it years ago and I came out as an I-N-F-P.
- (I) I am basically introverted (though not extreme)
- (N) I process information intuitively.
- (F) I make decisions primarily by feeling.
- (P) I tend to be perceiving in how I order my life.
Idealistic, loyal to their values and to people who are important to them. Want an external life that is congruent with their values. Curious, quick to see possibilities, can be catalysts for implementing ideas. Seek to understand people and to help them fulfill their potential. Adaptable, flexible, and accepting unless a value is threatened. (The 16 Types described)