That was the topic of a recent Quora forum (by the way may I officially announce that Quora seems to have succeeded? Would it be so bad to spend less time with your Google Reader and more time browsing Quora?), and here was the top pick:

“I do not know where family doctors acquired illegibly perplexing handwriting; nevertheless, extraordinary pharmaceutical intellectuality, counterbalancing indecipherability, transcendentalizes intercommunications’ incomprehensibleness.” (Dmitri Borgmann, Language on Vacation: An Olio of Orthographical Oddities. Scribner, 1965) This is a ‘rhopalic’ sentence: A sentence or a line of poetry in which each word contains one letter or one syllable more than the previous word.

File under “Very good sentences’! If I understand the Quora system correctly, that was from Ramnath Ragunathan.

Nishit Jain has the runner-up:

Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo. No, really. There’s a whole Wikipedia page on it – Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo The sentence’s intended meaning becomes clearer when it’s understood that it uses the city of Buffalo, New York and the somewhat-uncommon verb “to buffalo” (meaning “to bully or intimidate”), and when the punctuation and grammar is expanded so that the sentence reads as follows: “Buffalo buffalo that Buffalo buffalo buffalo, buffalo Buffalo buffalo.” The meaning becomes even clearer when synonyms are used: “Buffalo-origin bison that other Buffalo bison intimidate, themselves bully Buffalo bison.”

The entire thread is worth reading, and in your spare time you can ponder why most of the best answers come from individuals with names from the subcontinent. Here is the contribution of Veekas Shrivastava, listed as an elementary school chess player (retired):

A little grammar puzzle: “that that is is that that is not is not that is it is it not” Correctly punctuated: “That that is, is. That that is not, is not. That is it, is it not?”

Here is from Sugavanesh Balasubramanian:

“However, this valorous visitation of a by-gone vexation, stands vivified and has vowed to vanquish these venal and virulent vermin vanguarding vice and vouchsafing the violently vicious and voracious violation of volition.”

So there.