This is what I have written in the About Me section in Facebook: "INTP Meyers Briggs "Preference-Type". It used to be INTJ. Heavens knows what it was before then and what it will become!"
Joking aside, here's a link to the INTP preference-type: http://typelogic.com/intp.html on Typelogic and a Portrait of an INTP: http://www.personalitypage.com/INTP.html. Check this site out: http://www.intp.org/images/intpcrossword.gif. And - let's not forget the Wikipedia: http://en.wikipedia.org/wiki/INTP.
The point being...that if Facebook or MySpace (and other online social communities and such) provide the option for users and customers to identify their personality preference types, the "personalization" may help marketers identify their audience and pitch their brands.
Socio-personal metrics could be developed too for use in the social computing/media context.
Jungian functional preference ordering for INTP:
Dominant: Introverted Thinking
Auxiliary: Extraverted Intuition
Tertiary: Introverted Sensing
Inferior: Extraverted Feeling
Recommended Reading: "Type Talk At Work" - Otto Kroeger, Janet M. Thuesen, Hile Rutledge
Here's a great site with loads of personality tests to gleam ideas from: