If you think MyersBriggs is interesting, check out the EnneaGram... There is an excellent book by Don Richard Riso called "Personality Types - Using the Enneagram for Self-Discovery". It can be an intense study into the self, and at the same time, it can bring a higher level of self-awareness and self-acceptance... along with a broader appreciation and sense of humor about who we are as humans. I like this book because it describes all aspects of each type - the strengths and the weaknesses, how each type responds to stressors in life, how each type acts/reacts at different levels of integration/disintegration, and how each type relates to the others. Personally, I think it's a fascinating study of the human psyche.

The Enneagram consists of nine core personality types. It describes each core personality type, and the two other main sub-types we lean towards when we are stressed, and when we are happy (or in Heart, as it's sometimes referred to). It is a great tool for understanding and dealing with people we may have difficulty with, including ourself (!). We carry parts of all of the nine types, but there is one that is predominant. For example, I am a Nine, and when I'm stressed I go to Six; when I'm in "heart" or happy, I spend more time in Three. It is a definite pattern to my behavior - I'm amazed at how accurate the Enneagram is... I have several friends with the same experience/opinion.

I believe that Jung and Myers/Briggs incorporated the Enneagram in their work - it's been around for a long time - perhaps since the time of the Sufi... 
-- Adriana
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I find the the book by Rohr and Ebert ''very'' valuable. German original: ISBN 353262088X (you can find it at http://www.amazon.de, the ISBN is correct) English translation probably: ISBN 0824511859. 
-- FrankGerhardt
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See 

http://www.enneagraminstitute.com/

http://directory.google.com/Top/Science/Social_Sciences/Psychology/Personality/Enneagram/

http://dir.yahoo.com/Society_and_Culture/Religion_and_Spirituality/Faiths_and_Practices/New_Age/Enneagram/

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See also http://www.skepdic.com/enneagr.html.
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CategoryBook CategoryPsychology