I am an INFJ! We are the most rare of the personalities. Only 1% of the population Creative, nuturing, introspective, and a "I have to save the world" attitude. I'm pretty sure they say Mother Theresa and Ghandi are INFJ's.
When I took it in college, I was INFP. I wonder if it can change as you get older. You're still you, but you might answer questions differently based on life experience.
Using this I got ISTJ. This is the first time that I've taken this type of test. I thought it pegged me pretty well.
ISTJ here too, I took the test as part of a work seminar - I was the lone accountant in a group of actuaries. As I recall, lots of I types in that group. This pretty much describes me too. I like people, and don't mind meetings, but I need alone time frequently.