I'm sure from time to time all of have taken some kind of personality tests. It is 'most inescapable with the net being so full of them & the amount of unsolicited mails one possibly gets from these sites. They judge everything from your ability to turn an omelette to your expertise on leaving a peck on the neck.
However, some are, if not exactly informative, generally accepted to be of value or definitive of some kind of a benchmark. For example, the classic IQ test. The Intelligence Quotient has been believed to be a reliable indicator of a person's intelligence - for a while now - & in some really dubious studies, has been used to prove the superiority of one 'race' over the other. And this in spite of the fact that there is no scientific definition of race.
The Myers Briggs test is an interesting one. It is based on the psychological types defined by C. G. Jung & tries to arrive at the psychological type of the person taking the test by having her answer a series of questions. You can take a free online version of the test here.
It might sound like a far-fetched idea, & my own knowledge on the subject is very limited, but it appears that the test score has implications for your everyday life & career. In fact, this project management book recommends that teams be formed in the light of MBTI scores of the candidate team members.
I also believe that the online version is prone to errors of judgment & your online score is only indicative of your desired or perceived psychological type & it is only after working with MBTI consultants can you get an idea of your true type.
Also, with 16 MBTI types, assuming that people are distributed with equal probability across all types, the average % of people in any type is about 6%. So before you get glorious ideas & muse on the rarity of your psychology, laugh!