There is an MBTI test on facebook that isn't especially well designed in my opinion, but it's not terrible. It seems to mistype about as frequently as the standard MBTI.
However, it has an interesting companion function that allows people to take a test to type their friends. Obviously, self opinion and the opinion of others is likely to vary, but I find the possibility of others taking a quiz to show their opinion of you interesting, especially for those who have ambiguous self opinions.
So far, most of my friends' results type me as ENFJ, with a few typing me as INFJ. Not unsurprisingly, my external perception is more extroverted than my internal perception.
This approach could become an interesting tool if designed properly.
This..most people would immediately type me as T type.
Actually, now that I think about it, depending on the person I will appear as nearly any J type. More so with IJ's.
People who are Ni dominant, or secondary will likely say I am also an N. Ne and the S's likely not. It more has to do with recognizing the feel and apperance of Ni, which I know I have. People I speak to will say I am an F because I tend to be warm once I know them. People will say I am an E when I am in group meetings, games, ect. (parties wont cause this though, I am usually much more I in parties).
Here an order of what I think people would most often guess me as, if I include every factor I can think of, and then say how prevelent that factor comes into play:
ISTJ > ISFJ > INTJ > ENFJ > INFJ > ENTJ > ESFJ > ESTJ
I don't think anyone would ever in a million years guess me to be a P type, if they do they don't know me at all.
My external perception to most people would likely be that of an ISTJ (wrong, but I assume that is what they would see), so I doubt it would work very well for everyone.