Now, I've taken the Myers-Briggs tests twice so far, and have come out an ENTP and today I was quite delighted to find out that ENTP maps to the Inventor Rational type. There was also a list of famous Inventor Rationals, and Feynman was one of them.
Not that I have a claim to a Nobel Prize, but such company is flattering :)
I actually found the Keirsey temperament explanations, though riddled with typos (and biographical inaccuracies on celebs' pages) much more revealing than the Myers-Briggs ones I read before.
The Keirsey site lets you determine which of the four main temperaments you are for free, and wants to charge you for finding out which exact sub-type you are. If you know your Myers-Briggs type, you can simply find which sub-type your four-letter type maps to on their temperament overview pages.