I think Porsche is probably right.

And fusthustler is wrong: tautology has nothing to do with grammaticality.

I think "a whole nother story" is tmesis. My favourite example is Luke's "but that's a whole nother year!" in Star Wars.

From Merriam-Webster's Concise Dictionar of English Usage:

"...will you go and see it and tell me whether they murder it or not" - GB Shaw, letter, 28 Nov 1895

"...never knew whether or not to insert the names of his parents" - John Updike, Couples, 1968

The option of mitting "or not" only exists when the clause introduced by "whether" serves as the subject of the sentence or as the object of a preposition or verb. When the clause has an adverbial function, "or not" must be retained:

"Whether or not one agrees with Vidal's judgments, there are some trenchant formulations" Simon 1980

No, I don't think that we would "all do what we want" without explicit rules. Society exerts norms on grammar. Most languages have no writing systems or prescriptivists, and yet the speakers understand each other.

It's possible that it is an adverb in this context. Not all adverbs end in "ly" - for instance "fast", "slow", "flat" are adverbs.

OK, my examples from Marlowe and Fletcher are usages that Kyle would say are correct, so they are irrelevant here.

Kyle, your definition of "grammatically correct" is ignoring the facts. And what is the point of a grammar that ignores how language is used? Bismarck's post above on registers is also worth reading.

Kyle,
The prescription that nominative pronouns must be used after the copula began in the 18th century. As far as I can tell, it was based on an analogy with Latin or a misguided concern about "logic".

http://www.bartleby.com/185/41.html
Marlowe used “is it him you seek?”, “’tis her I esteem” and “nor thee nor them shall want”; Fletcher used “’tis her I admire”; Shakespeare himself used “that’s me.”

Instead of trying to apply an irrelevant argument about subject and object, look at the facts. The fact is that people use the object pronouns after the copula. This is normal English.

Would you say "The winner was I" or "The winner was me"? I would never say the former. It sounds strange to me. As a native speaker of English, I'm trusting my intuition on this.

If we follow the prescription that we must use nominative (or subject) case after "be", we get ridiculous things like this:

"Here's a photo of my old hockey team."
"Which one of these players is you?"
(pointing) "Oh, that's I."

I didn't say that "water" and "sand" are countable nouns. They are uncountable nouns, also called mass nouns.

http://en.wikipedia.org/wiki/Uncountable_noun

It's not a problem of being unable to distinguish between countable and uncountable. I find it hard to believe that people don't know the difference between countable and uncountable nouns. Otherwise they would say things like

the number of water in the ocean
the number of sand on the beach

And they don't. Instead, as porsche says, "amount" and "much" are shifting to take some of the load of "number" and "many". There is no trend in the opposite direction.

Then why do I never say "That's I"?

When am I supposed to use the subject case pronouns after "be" and when am I supposed to use the object case? The "rule" is impossible to follow.