Short quote: literally
From the The Mirriam-Webster Dictionary of American Usage, two paragraphs from a page-length discussion of the word literally:
Now a word about the critics. The chief assertions they make are that the hyperbolic use f literally is a misuse of the word or a mistake for figuratively. As we have seen, it is neither; it is an extension of intensive use from words and phrases of literal meaning to metaphorical ones. It is a not altogether surprising development from Alexander Pope's not quite literal "literally another yesterday."
If the hyperbolic use of literally is neither a misuse nor a mistake for some other word, should you use it? The point to be made here is that it is hyperbolic, and hyperbole requires care in handling. Is it necessary, or even useful, to add an intensifier like literally to a well-established metaphorical use of a word or phrase? Will the use add the desired emphasis without calling undue attention to itself, or will the older senses of literally intrude upon the reader's awareness and render the figure ludicrous, as was the case when a football play-by-play man we heard some years ago said the defensive linemen had "literally hammered the quarterback into the ground"?