Despite some ongoing controversy about the construct validity of Myers Briggs Type Indicator, my impression is that the MBTI is more popular than ever. I believe there are several reasons for its popularity.
First, the Myers-Briggs is widely available for use in non-clinical settings. It can be administered and interpreted without the supervision, scoring or interpretation of a psychologist. The administration is relatively quick and scoring is simple. There is even a self-scoring form of the test (Form M). Interpretative narratives for each of the 16 possible MBTI profiles are available and easy to understand. The narratives range from general and brief, to more extensive. Additional scores and reports can be generated for particular concerns such as relationships or career.
Jon at Brain, Mind and other things posted a brief discussion of the Myers Briggs Sensing and Intuitive functions. He's an INFP. Most recently, on Form M, I'm an INFJ with three of the four functions (IF&J) in the Slight range and N in the Clear range. That's the same as my past results with the old Form F.
There is a similar typology test on-line here. I can't vouch for its reliability as a parallel form of the Myers Briggs, but my on-line results were the same as my results on both the old MBTI Form F and the newer Form M. If you take the on-line version, you'll get a four letter profile. Just type the four letters (without spaces in between) into the Google search box and you'll find an assortment of narrative descriptions of your type.