reapersaurus & Daniel: I agree that informing players of changes/limitations - and the DM of "smacks" - beforehand is optimal.
Further, yes, no DM can, especially without some practical experience with the game system, know all possible "tricks" that could be too much for their campaign. Being a regular in a place like EN World helps here, of course.
ConcreteBuddha said:
Example: We have a player in our group who will only play archers. Or more specifically, Fighter/OOBI/Deepwood Sniper/AA/Peerless Archers. With no regard to a character concept besides doing lots of damage [more damage than anyone else]. He also expects to have GMW, on both his arrows AND bow. If a caster does not want to give him GMW, he gets angry. Yes, he is a bad player, but he is not bad enough to kick him out of the group [ah, if life were only so simple].
There are multiple ways to handle this:
1) Have all the NPCs use wind wall/warp wood/cover/sunder his bow.
2) Nerf GMW.
3) Nerf the PrCS.
4) Let it go while the other players are bored beyond belief. (Which has happened. Multiple. Times.)
What would you do in this situation? (I know what I would do IMC. Unfortunately, I am not the DM of this specific game, so none of the above options have happened.)
In-character, you could ask him whether he's so insecure about his archery skills (or such a bad shot) that he
needs GMW to succeed.
If he persists, suggest to him (still IC, of course) that he should leave the party for a while to hone his skills (not to mention his self-confidence) to a useful level.
As a DM, I'd have little problems with that guy.
First of all, the more ruthless of my players' characters would probably kill such a character very soon anyway, given that he's not only a spotlight hog but apparently also an arrogant crybaby.
That aside, he's really a one-trick pony (although possibly slightly more flexible than most, given that at least one of these archer PrCls enables you to shoot your bow in close combat without incurring AoOs). And one-trick ponies only shine under optimal circumstances.
Most campaigns shouldn't constantly feature these conditions, though; put that William Tell wannabe against skeletons (who only take 1/2 damage from piercing weapons), bandit archers (or Evoker pyromaniacs

) with cover,
mirror images,
invisible foes, suboptimal lighting and air conditions (e.g., darkness and medium winds, respectively), grapple attacks, creatures with Deflect Arrow,
dispel magic on his bow and/or arrows, or any of a hundred other situations/enemies that are less-than-optimal for archery, and he won't shine quite as brightly.
Of course, constantly sending him in battle against skeleton (i.e., bone creature) Evokers with cover,
mirror images, the Deflect Arrows feat, who
dispel the GMW on his bow and arrows, and their
invisible buddies who grapple the archer, at night and in a strong wind, is suboptimal
DMing!

(BTW, some campaigns certainly
do almost always feature optimal conditions for some one-trick pony types; these can be a bit more problematic. Also, depending on his exact PrCl and level in it, he can deal with some situations more easily. For example, a dwarven archer doesn't have as great problems with darkness.)
Anyway - apart from situations in which his strengths aren't as useful, there are also situations where his weaknesses are targeted by his opponents - and one-trick ponies usually have some weak points, especially given how min/maxed they tend to be.
For example, Will saves probably aren't his strong point - so spells and other attacks that require them are particularly dangerous to him. Another weakness of mr. uber-archer is that, when deprived of his bow (or even just his ammunition - which doesn't tend to be infinite), he can't do very much
at all, compared to a less specialized fighter-type, given that many (if not most) of his feats and class abilities probably aren't very useful in melee combat. (Also, in a game system with damage to specific locations, having a hurt hand or arm is very detrimental to one's archery skills; certain medieval rulers had very strong reasons for cutting off a few fingers when they released captured bowmen... Anyway, this mostly isn't applicable in D&D, of course.)
Important side note: I'm very much a "status quo" GM - i.e., I don't tend to tailor encounters to specific PC qualities, whether these qualities are positive (e.g., one PC is the greatest archer ever) or negative (e.g., no cleric or paladin in the party).
Thus, I certainly do
not advocate constantly using the situations I outlined above for the sole reason of "nerfing" the super-archer.
Instead, I want to illustrate that problems with such characters only occur when the conditions under which they fight are optimal for their tactics. That is, when the encounters the party faces don't vary enough to make such specialization impractical.
Trust me, in campaigns where fights against skeletons are very common (especially if they also caused fear), such uber-archers won't thrive. Likewise in a picaresque campaign whose encounters vary wildly in style.
There are three reasons for combat conditions not varying too much: GM laziness; setting requirements; and GMs tailoring encounters to enable archer-boy to shine (*shrug* it happens; I've seen it more than once).
Still, if the one-trick pony becomes real a problem, the GM has to either "nerf" him or put him in less optimal combat conditions more often - whether that just means not being as lazy (e.g., always considering weather conditions rather than just glossing over them - which can make quite a difference for an archer) or even consciously creating adventures which include more challenging situations.
Of course, if the archer constantly wins, that ought to have negative consequences of its own...
See, success makes you renowned. Therefore, success at adventuring makes you a renowned adventurer. But constantly slaughtering your opponents with superhuman archery tricks makes you a renowned
archer.
And if you're known as the world's greatest archer, your enemies will take steps to protect themselves against you (providing they know - or even just suspect - that they might run into
you). Further, pre-emptive attacks will rise in frequency as well; if you're up to no good and know (from his reputation) that that mega-archer probably will sooner or later interfere with your nice plans of bringing the demon-lord Baphomet into this world, you're well-advised of taking care of that troublesome meddler
first. And, if you're smart, you'll do it in a way that a) can't be traced back to you (e.g., cast
change self and hire an assassin who you tell nothing about your plans - or even lies that will make the do-gooder attack your other enemies, if he interrogates the would-be killer) and b) negates your enemy's obvious strengths and targets his obvious weaknesses (or even the less obvious strengths and weaknesses, providing you know them - which the GM should adjudicate fairly). Or maybe murder some of your other enemies in a way that suggests that archer boy, rather than you, was the culprit. This is especially nasty if you can sicc an organization that he won't want to fight on him (e.g., a good-aligned organization, for most PCs).
Example for a good assassination attempt on archer boy:
Have someone pay drinks for everyone at his favorite tavern that evening. That way, two things are accomplished: a) distraction (many people are around, it's noisy, etc.) and b) chances are good that he or his allies won't be in the best fighting condition that night. (Note: The person who pays the drinks shouldn't know anything about the assassination plot, so provide some plausible lie as explanation both for them and for everyone else - e.g., a celebration because of some religios holiday, or a birthday, a business success, a childbirth, or whatever. Further, this person should not, under any circumstances, enable your enemies to find out that you ordered this. Further, don't poison the drinks in any way; it isn't worth the risk.)
Then, have your hired assassin break into the place where your enemy sleeps.
An interesting way to commit the murder: Equip the assassin with a
bag of holding (or like item) containing
reduced skeletons and some item of
dispel magic (to
dispel the
reduce effect) that he can use (Silent Spell on the
dispel magic is especially handy, BTW).
Then, if possible, the hired murderer grabs your enemy's bow and has the sleeping (and hopefully drunk), armor-less archer be grappled and strangled to death by the skeletons. He can also help the skeletons if necessary - and if he can't grab the bow, the skeletons still aren't too easy to hurt.
Silence and
(improved) invisibility are nice to have, too.
(Note: This works best if you're a cleric or at least have one handy, of course; otherwise, the skeletons can be hard to come by. You also need a Wizard or Sorcerer for the
reduce. Still, substitute the skeletons with something else - or just a plain old murderer who CDGs the sleeping enemy - and it still works like a charm. Of course, against enemies who sleep in places you can't reach - which is unlikely if you can get
dimension door or similar effects -, all this won't help much.)
Whew! That was long...
I hope it gives you some inspiration, though.
PS - Sometimes, you have to "nerf" a class, feat, spell, or whatever, of course - even if only because a certain campaign requires it (e.g., magically creating water is harder in Dark Sun because it's a desert world and water is hard to come by).