In case anyone else wants to take the test and find out their Myers-Briggs Personality Type...http://www.humanmetrics.com/cgi-win/JTypes2.asp
I debated about posting it, but I'm an ENFJ, I couldn't resist. ;)
Incidentally, I first took this test when I was in high school (20+ years ago) and I was, at the time, very strong on the Introvert scale...I retook it many times, several years apart, and by the time I was in my late 20s I had completely shifted over to a strong Extrovert.
Looking back, the difference in my scores had very little to do with what I wanted---it had to do with what I was capable of at the time. I have always had a dominant need to be around people---I don't ever crave alone time, really. The way I look at it is I'm with myself all the time, and in my head I never shut up, so why on earth would I need more time with me than I already have?
I felt that way even when my Introvert score was high---I was just too shy at that time of my life to seek out as much interaction as I craved. I'm not sure what gave me the courage to eventually be bolder about social interaction, but I'm glad it happened, because I was an unhappy Introvert---a closeted Extrovert, basically.
As far as how this applies to writing, I find that interesting as well. I've written all my life, but it wasn't until I swung over to the Extrovert side that I began to share my writing with others. In school I even had a hard time handing in stoies/screenplays/etc to my professors---sharing them aloud in class or exchanging them with other students was beyond my capabilities. It wasn't until I got older, and more extroverted, and got involved with blogging/posting/writing groups that I finally became comfortable with other people reading my writing.
Granted, a lot of computer writing is done under a protective guise---there's some distance there (enough to keep my residual introvert feeling safe)---but it's still something I wouldn't have been able to do years ago (and not just because the internet didn't exist yet at the time!).