I ask good as every grammar book I’ve seen said "Use of the ! should be avoided as it is a very poor substitue for a better worded sentence.
Are there any other uses for the ! other than to show excitment and empasis?
Well without ! we couldn’t have !=, now, could we?
It’s used as a mathematical symbol; n! (“n factorial”). A factorial “is the product of all positive integers less than or equal to a given number and denoted by that number and an exclamation point.”
5! = 5 x 4 x 3 x 2 x 1 = 120
4! = 4 x 3 x 2 x 1 = 24
3! = 3 x 2 x 1 = 6
2! = 2 x 1 = 2
1! = 1
0! is “arbitrarily defined as equal to 1”.
And it is of course used for excitment and emphasis; you just don’t want to overuse it. “Oh, the humanity.” just doesn’t look right (let alone “Oh, the humanity?”)–it’s properly “Oh, the humanity!”.
Those same books also say that quotation marks always come in pairs!
So what are we saying here? That we can’t ever have a strong emphatic statement in a correctly worded sentence? Nonsense! I’ve checked a half dozen grammar & style sites and I don’t see anything of the sort! Except for some things about using exclamation marks in excess! Now that I tend to agree with!!!
I can think of no better use for an exclamation point than in a comic strip when it appears over some guy’s head after he’s seen something shocking.
I wish it could happen to me. That would be pretty neat.
Sorry, it’s not an answer (friedo stole mine), but this thread reminded me of something my brother noticed a few years ago. Has anyone ever read the cartoon strip “Mary Worth”? If so, have you ever noticed that they never, never, ever use periods to end clauses? It’s always a ! or a ?. It’s as if all the denizens of Mary Worth-land have two modes: inquisitive or emphatic. Nothing is ever boring. It annoys me to no end, for some reason.
NB: “never, never, ever” is an exaggeration. I have seen two periods in the strip - one apparently in response to a letter written to the authors by my friend and me.
Again, sorry to diverge from the OP.
Strunk and White, “The Elements of Style”:
(wrong) / (right) added as I can not easily reproduce the original !@#$!*&!! typography here.
Comic Books ALWAYS used to end their sentences with exclmation points. Fortunately, things have changed. Comic dialogue no onger seems as breathless as it once was.
As noted above, exclamation points are also used in factorials (5! = 120 I’m told it is a Britishism to pronounce this "5 Bang!). It should also be noted that a double exclamation mark can be used to indicate factorials involving only ever other term (6!! = 6 X 4 X 2 = 48).
Finally, although Strunk and White is a useful guide to good writing, we shouldn’t take their book as the final guide and arbiter. Strunk was a crotchety old guy whose notions of good writing correspond with those of most people, but if everyone obeyed his rules writing would be a lot less interesting. You won’t be pulled over and given a Writing Violation if you stoop to usin exclamation points in your writing. I do!
¡I like the Spanish version better, since you get the emphasis right away, when you need it most!
¿Why can’t English do that?
My point was that S&W (the grammarians, not the food canners) weren’t saying NEVER to use it, unlike the OP was suggesting, just that it should be applied to the right type of sentence. And of course, S&W isn’t a final guide and arbiter, but if you’re going to go get out a rule book, it’s one of the better ones. So there!
Not only a britishism, but a geekism too. Unix shell scripts written for the “bash” shell begin with “#!/bin/bash”, which is, of course, pronounced “hash bang slash bin bash”. 
(“hash bang slash bin slash bash” would actually be more accurate, but it just doesn’t roll off the tongue as well…)
I’ve taken a fair amount of math, and I’ve never seen this notation. In which particular variety of math did you encounter this?
I’ve seen it in a number of places. Look in the Penguin Dictionary of Interesting Numbers, for instance, or in Gradshteyn and Ryzhik’s book “Integrals, Series, and Products”.
I agree, Strunk and White is one of the better guides (in part because of its deliberately short length), but people DO tend to regard it as the Grammar and Style God. All I’m aying is that it’s not, and we should resist this.
(friedo mentioned this earlier, but in a way that may seem a little cryptic to the non-programmers among us.)
Some programming languages use a leading ! (pronounced “bang”, as mentioned above, though I usually say the simpler-sounding “not”) to show negation, thus the != operator is just a convenient way of saying “not equal to” without the convenience of symbol fonts.
Of course, it’s used with variables and expressions of all sorts too: if(!Thursday) == “If it’s not Thursday…”
There are other uses of ! in computer science, but I must confess that I’m not familiar enough with them to explain them yet.
There’s nothing wrong with the occasional and judicious use of exclamation points in prose. One good rule of thumb is only use it when quoting. (It’s OK if a character exclaims something, but if the author does it, he’s trying to countersink things).
And as for computer applications, most of the punctuation marks representable in standard ASCII have been pressed into service in many, many places to mean many, many things. People come up with lots and lots of uses for special characters, and there’s only so many available (this is why an operator-heavy language like c/c++ had to invent so many double character operators, and why c code ends up looking like line static if the programmer is primarily concerned with compressing their thoughts into as small a space as possible).
The use of ! for negation is well established, so in many programming and scripting languages (not ALL by any means) it will tend to be used as an operator to mean that.
One modern place it has started turning up is in XML/HTML metasyntax delimited by “<! … >”. If you look at the source of this page, you will note that it begins “<!DOCTYPE blah blah>”, which states that this page conforms to a particular version of HTML (hah! <-- grammatically justified exclamation point).
YES !
Concerning comic uses, let us not forget that “!” is an essential component of the quiz-bang, “?!”, which is indispensable for indicating startled bewilderment.
Obviously, I also use the hackish pronunciation “bang” for the symbol. IIRC, it predates the use of “!” as a negation, and was heavily used in the days of the old bang-path addressing system.
Oh, yes, the OT…I have used “!” purely for emphasis in papers for my collegiate honors courses, without drawing professorial censure. That either reflects inattentiveness on the part of my professors (shocking, in light of the material 
), or that they were of the opinion that this was an acceptable usage. YMMV