When I worked at Volvo, I had an opportunity to take a project leader course, which I did of course. The course included also to get to know yourself better and as a part of that doing a Myers Briggs Type Indicator test. In another course I took, this was also a part of the course and the Belbin test.

Person type indicators are useful when composing a project team. If you have the same type of people in a team you don't get the different angles you need to get the best result. This has been confirmed in many studies, according to the course leaders I had.

When I did the Belbin test, I was the typical PLANT (www.belbin.com) but also a Monitor/Evaluator. (Another link showing Belbin types.)

The Myers Briggs Type indicator test which we did, was a test consisting of 88 questions. We calculated the points according to what we had answered. I got the INTP profile the first time I did it. When I did it 1½-2 years later I got the ENTJ profile, which means I have become more extrovert than earlier,

Here you can find a simple and fast Myers-Briggs type indicator test, and here you can see what it means.
I did it now (Nov 14 - 2010) while searching for information to put on the page, and got the following results:

Your type is: ENTJ
Extraverted	Intuitive	Thinking	Judging
11%	38%	25%	11%