Hi Antem,
Okay, before I get to the real advice, I'll try to cover what you have asked outwardly (by that I mean that what you ask is usually different to what you want to really know, but we'll get to that).
The concept of "nerve-striking" systems is most commonly a misinterpretation of the Dim Mak concept, or the Kyusho concept (Chinese and Japanese variations there). The old story of the origin of Dim Mak is of a Chinese Martial Artist and Doctor who would practice striking the healing points he knew from his medical training in various ways (most commonly it is said that he used condemned prisoners to "practice" on), as he knew from experience that he could influence the flow of internal energy by stimulating the meridians and points in different ways. By stimulating the point in one way, the flow increased, in another it slowed. So what would hitting it do? Well, the results ranged from discomfort, to pain, to damage, to death. The doctor also used his training to develop resuscetations and recouperations from being hit in these places, as much as he could, but for the points that left the victim deceased, there was no fix. These became known as Irretrievable Death Point Strikes, later refered to as Dim Mak.
A quick note on these points. They have been covered in mystique and myth for generations, leading to tales of "if you touch the other person in this place at two am on a full moon, then two days later they will drop dead and there will be no trace as to why..." Not exactly realistic. Most of the "death strikes" are just simple things like crushing a throat, a good, solid hit to a highly vulnerable spot. There are high-level aspects in which timing is important, but leave the myth aspect behind.
This knowledge has formed the base of many arts, such as Hsing-I, Ba Gua, and Taiji Chuan, however I feel that that has more to do with the cultural philosophies of energy channels and meridians, so the idea and concept of effective targetting was simply described in a manner that the Chinese people studying could immediately relate to (however, being Westerners, we are not brought up with the same cultural ideas, so it becomes "mystical" and "exotic" to us, which simply adds to the appeal for many people).
Within Japanese arts, this targeting concept is refered to as Kyushojutsu. It is found in most arts, ranging from Koryu systems (armed and unarmed, armoured or not, and changing for the particular system based on what was commonly available as a target at the time) through to being present in more modern arts like Judo, Aikido, and Karate. Whether or not openly taught or discussed is dependant on the teacher and art, but if it has targeting, it's there. And if you're just being taught to swing wildly, I may suggest another school. Within the Ninjutsu community, for instance, it is very openly discussed, with a number of our schools including a kyusho chart or list in the transmissions, within most Karate schools it is more a high level teaching, but is certainly still there. The Bubishi is a classic text which covers this aspect of Karate for example.
Now, we'll move on a bit. As stated, any school that teaches targeting is teaching you this idea in some form (even boxing, going for a knock out punch, whether to the point of the chin, or a body knock out, is just a variation of this very concept, expressed in a Western understanding of anatomy rather than an Eastern philosophical phrasing, and restricted based on the requirements of the system such as the gloves and legal targeting). So I wouldn't be too concerned about a specific art. I would rather invite you to look around your local area and see what arts are being taught. Then visit as many schools as you can, talk with the instructor, and go with the one who you feel the best about (what he or she is teaching, how they interact with the students, how the entire school feels etc). This is your best bet, and will give you the most positive launch into martial arts. Of course, if one art speaks to you more, look to that first, if it is available, but don't discount anything else.
Now we'll get to the crux of the matter. Why do people start martial arts? What draws them in? Well, in a lot of cases, it is a feeling of a lack of personal power, or control over things. So in order to get that feeling of power, people look for what they percieve as being powerful, and unfortunately these days a lot of that perception comes from things like movies and video games (small aside, I was watching a documentary on XMA last night, now, I'm a self confessed martial arts snob, but those guys make me damn angry. That is the ultimate in movie fantasy based "martial arts". That ain't martial arts, it's gymnastics, and that guy throwing his "katana sword" up in the air so it spun around said one more word about how he did itout of respect for the weapon and for the samurai of old, I was going to throw something at the screen! Then I remembered I could chagne channel, and the world brightened... okay, got that off my chest!). Coming from such a source leaves gaps in reality, and can lead people to search for things that aren't there, or are there in such a different way that no matter how impressive it isin reality, it just doesn't match up to the movie in your head.
When it comes to things like "pressure point striking" and similar, this is not uncommon. A touch of reality, though. Targeting is vitally important in martial arts, but it's only part of the entire equation. This is why you have been advised that many arts will include it, but there isn't an art that is just striking points. And it should always be remembered that striking these points is not a magic formula for success or devestating power, you can miss, and the opponent could not feel the effects as much as you hope due to alcohol, drugs, or just plain old fashioned adrenaline. In the dojo these tactics have a much greater result than they will on the street. Just so you know.
So what are you really looking for? Well, if you are asking about nerve strikes, then typically you are feeling (most commonly unconsciously) powerless against a potential opponent, and are looking for a way to feel safe, secure, and powerful. You are most likely not the biggest guy (neither am I, actually), and are looking for a way to overcome the feeling of being powerless that that can bring. Cool. The thing to do here is to realise that you are looking for these unconscious feelings to be looked after, and that is done by chosing an instructor you can respect and learn from, whether they teach specific nerve strikes or not.
Hope this made some sense to you.
... just effective :EG:
