I can tell you a bit about INTPs. The INTP is one of sixteen Myers-Briggs / MBTI personality types, and is sometimes also called either the "Architect", "Thinker" or "Wizard" type. I guess it's the MBTI personality type I belong to; lame online personality tests are pretty consistent in claiming it is, and it's the one I find I have most traits in common with. I'll be the first to admit I don't take Myers-Briggs typing all that seriously, though. The INTP is one of the rarest of the types.
So, what about these INTP characters? As all Myers-Briggs types, the letters are defined from a type's functional preferences (a concept derived from C.G. Jung's psychology). In the INTP's case, these preferences are:
So the INTP is a perceptive, introverted, intuitive thinker type fellow, right? Well, yes, but since Myers-Briggs terminology uses these terms in a somewhat different manner than their everyday meanings, it isn't necessarily the most fitting description. You might want to read about Jungian functions or about Myers-Briggs if you want to grok the Myers-Briggs versions of these terms. To degrees that vary wildly from individual to individual, an INTP will display traits associated with the related types ENTP, ISTP, INFP and INTJ.
Famous INTPs include Albert Einstein, Socrates, Rene Descartes, Isaac Newton and Tiger Woods, and some famous fictional INTPs include Commander Data, Linus from the Peanuts and possibly Gandalf the Grey (the jury is still out on whether he is most like an INTP or an INTJ).
Anyways, about these INTP fellows. I guess the trait that most defines the INTP mindset is the tendency to analyze and try to understand anything that catches their fancy. To many INTPs, the quest for understanding is the main driving force of their lives, and it permeates more or less everything they do and like. From taste of music (they usually hate simplistic music, delighting in complex compositions that they can have fun picking apart with their brains) and fiction (fantasy and science fiction are favourites, especially books or films that contain large and complicated fictional worlds, like the Lord of the Rings or Star Trek), to choice of education and professions. Although they're usually called the "Thinker" or the "Architect", I suspect the people who wrote that nonsense were trying to be politically correct instead of just calling the INTP the "Geek" (although that wouldn't really be fair -- INTJ's ENTJ's and ENTP's are often some pretty major geeks as well).
Since they delight in logic and complex systems, I guess it comes as no surprise that many INTPs are interested in computers, mathematics and other sciences. They generally like playing with ideas, meaning that they're the great bane of people who hate arguments -- it is not unheard of for INTPs to play the Devil's Advocate just to get a good and fun argument going. They tend to be among the less socially oriented of the MBTI types, and if an INTP goes to a party or a similar social situation, he will often feel dreadfully out of place, right up until he locates someone he can discuss C programming, quantum bogodynamics or Lord of the Rings trivia with. If that happens, you're lucky if you can drag him away four hours later. For his part, he's lucky if he has noticed that four hours has passed.
INTPs tend to be messy and disorganized, owing to their preference for Perception. To an INTP, an item that is not in use more or less ceases to be even visible. Mess piles up in monumental hoards, turning desks, rooms and whole apartments into something that mostly resembles Baghdad By Night, 2003. An INTP will tell you that only a fool tidies up, a genius rules over chaos (he will then promptly forget to tell you that his rule over that chaos is tenuous, at best). Their penchant for being less-than-orderly carries over into many aspects of their lives, for indeed they tend to loathe living after a strict plan of any sort, preferring to be free to do whatever feels right at that particular moment in time. Don't let their outward disorderliness fool you, however. They think in very well-structured patterns, and while an INTP computer geek's cave may be hidden under mounds of mess, his hard drive's files will be meticulously ordered and his code elegant.
Possibly because the INTP loathing for living under strict systems, they tend to be highly anti-authoritarian. Not necessarily to the point of being political anarchists, but INTPs tend to despise those who would give them orders. They have little if any interest in giving other people orders either, so they make as poor leaders as they do followers. Generally, a wise corporate overlord (OXYMORON ALERT!) would probably find that it's best to leave them to their own devices, pondering and talking to themselves in some solitary dark cave, with only occasional steering. They don't really understand the concept of rank, and will talk to their bosses as equals or even inferiors (a tendency that annoys many managers of computer programmers no end -- predictably, it's a field that has a large share of INTPs and related types).
The archnemesis of the INTP is boredom, and indeed boredom is what kills most of the projects they set out on. In the initial phases of problem analysis and solution design, the INTP can become so engrossed in his machinations that he will forget to eat, drink, wear pants and such. However, soon after the problem is understood and the INTP realizes that he can solve it, it becomes boring and he will lose his enthusiasm. A smart INTP knows this, and uses a strategy of partitioning and rotating his projects so that he'll always be messing around with something that his brain thinks is a new, exciting problem. I guess that last sentence also shows a typical INTP tendency -- they're constantly second-guessing themselves, observing their own thoughts as a detached observer would. They're not at all above playing tricks on their own brains, for fun and utility.
I guess I could write a lot more about this personality type, but It's Not That Popular, so I'll move off and let you go back to your noding.