Eric Meyer pointed me to an interesting personality test. Here is what I got:

Wackiness: 44/100 Rationality: 40/100 Constructiveness: 30/100 Leadership: 34/100 You are an SEDF--Sober Emotional Destructive Follower. This makes you an evil genius. You are extremely focused and difficult to distract from your tasks. With luck, you have learned to channel your energies into improving your intellect, rather than destroying the weak and unsuspecting. Your friends may find you remote and a hard nut to crack. Few of your peers know you very well--even those you have known a long time--because you have expert control of the face you put forth to the world. You prefer to observe, calculate, discern and decide. Your decisions are final, and your desire to be right is impenetrable. You are not to be messed with. You may explode.

Hmmm, I agree for the most part (definitely Sober), although I would not have considered myself emotional. So with a little adjustment I would get this:

You are an SRDF--Sober Rational Destructive Follower. This makes you a font of knowledge. You are cool, analytical, intelligent and completely unfunny. Sometimes you slice through conversation with a cutting observation that causes silence and sidelong glances. You make a strong and lasting impression on everyone you meet, the quality of which depends more on their personality than yours. You may feel persecuted, as you can become a target for fun. Still, you are focused enough on your work and secure enough in your abilities not to worry overly. You are productive and invaluable to those you work for. You are loyal, steadfast, and conscientious. Your grooming is impeccable. You are in good shape. You are kind of a tool, but you get things done. You are probably a week away from snapping.

Ok, so the first one was closer, but I'd say I fit somewhere in between the two.

Update

Just for kicks I took the Better Person quiz as well. The result:

Your score as a human being is 80.35. You are close to ideal. So close, and yet so far. Amusing, really, to watch someone squirm so close to the vaunted ranks of perfection and still remain so very, very ordinary. It is all one can do to keep one's ingratiating smile from polluting one's perfect face. Actually, one recommends you take the quiz again and lie a little.

Now that is scary. Right on. And the suggestion is so tempting. But. I. Will. Resist.