trait theory web site

Here's a trait theory site with a free test:

http://www.outofservice.com/bigfive/

The Meyers-Briggs (MBTI) is based on preference theory. I happen to like the Meyers-Briggs personally, probably because I've used it and thought about it so much. But psychologists tend to poo-poo it in favor of trait theory and the "Big Five".

Here is the basic difference:

The essential difference between the trait theory and type theory is this: type theory views characteristics of people as discrete categories whereas trait theory views these same characteristics as part of a larger continuum. For example, where a type theorist would claim that introverts and extroverts are two types of people, a trait theorist would claim there is a gradient leading from introversion to extroversion and it is possible for individuals to fall somewhere in the middle. 

from: http://blog.motivemetrics.com/Psychological-Traits-vs-Personality-Type-Theory  

I recently read a book based on the Big Five - Me, Myself, and Us by Brian Little. Very good. A bunch of fun exercises to test your placement.