How much of that do I agree with?

Reading over some of the INTJ descriptions, I came across some statements that do indeed reflect the way I think:

Natural leaders, Masterminds (INTJs) are not at all eager to take command of projects or groups, preferring to stay in the background until others demonstrate their inability to lead.

This describes me surprisingly well... I didn't even think about it in this way beforehand. I usually think of leader types as charismatic people who inspire trust and confidence in their followers; ones who can connect well with people and know how to motivate them to do their best. Since I have very little charisma and am lacking in people skills, I feel like many of the leadership scenarios I find myself in are primarily task-driven - getting things done because that is the stated goal. I think I have a lot to learn in the definition of leadership where the leader is truly the servant of those he leads, enabling them to grow and to do the tasks that need to be done.

INTJs know what they know, and perhaps still more importantly, they know what they don't know.

This is probably one of the more important lessons I've learned in the past five years or so - to not be afraid to say "I don't know." The world isn't going to end because I can't solve every problem or answer every question. Even more than that, it has been an eye-opening experience to realize that much of the time, it is important to say that I don't or can't do something in order to give someone else the opportunity to fulfill potential that they have in that area. "It is more blessed to give than receive" - Acts 20:35. If I'm taking every opportunity to do something, particularly when it's not in my area of expertise, I may be denying someone the blessing of being able to give of their abilities and talents in that area.

In the broadest terms, what INTJs "do" tends to be what they "know". Typical INTJ career choices are in the sciences and engineering, but they can be found wherever a combination of intellect and incisiveness are required (e.g., law, some areas of academia).

Hm... science and engineering... sounds familiar...

A longer quote:
Personal relationships, particularly romantic ones, can be the INTJ's Achilles heel. While they are capable of caring deeply for others (usually a select few), and are willing to spend a great deal of time and effort on a relationship, the knowledge and self-confidence that make them so successful in other areas can suddenly abandon or mislead them in interpersonal situations.

This happens in part because many INTJs do not readily grasp the social rituals; for instance, they tend to have little patience and less understanding of such things as small talk and flirtation (which most types consider half the fun of a relationship). To complicate matters, INTJs are usually extremely private people, and can often be naturally impassive as well, which makes them easy to misread and misunderstand. Perhaps the most fundamental problem, however, is that INTJs really want people to make sense. :-) This sometimes results in a peculiar naivete', paralleling that of many Fs -- only instead of expecting inexhaustible affection and empathy from a romantic relationship, the INTJ will expect inexhaustible reasonability and directness.

Probably the strongest INTJ assets in the interpersonal area are their intuitive abilities and their willingness to "work at" a relationship. Although as Ts they do not always have the kind of natural empathy that many Fs do, the Intuitive function can often act as a good substitute by synthesizing the probable meanings behind such things as tone of voice, turn of phrase, and facial expression. This ability can then be honed and directed by consistent, repeated efforts to understand and support those they care about, and those relationships which ultimately do become established with an INTJ tend to be characterized by their robustness, stability, and good communications.

Yup, this sounds just about right. I am willing to admit that I don't know anything about social rituals, particularly in the context of a romantic relationship (the language of the giving of flowers, for example, is something that is totally and utterly beyond me). Plus, I generally assume that most people will make sense at some level - and I'll work at trying to understand them. Thing is, as George pointed out (BTW, George has a blog now!), sometimes women just don't make sense. Ah well. I suspect this is an area of callowness in my personality that could have been different had I grown up with a sister, but hopefully I'll figure something out eventually.