Naysayers still dismiss Twitter as a platform for people who post self-promotional links or trivial details about their daily lives -- this tuna sandwich is tasty! --- but there's no denying its growth.As we reach the halfway point of 2011, users of the microblogging service now post 200 million tweets a day, Twitter announced in a blog post Thursday.

That's up from 65 million tweets a day a year ago.Even in little 140-character bites, that's a lot of verbiage. Twitter offers some context on this: Assuming the average tweet is 25 words, that means that "every day, the world writes the equivalent of a 10 million-page book" -- or 8,163 copies of Leo Tolstoy's epic novel "War and Peace."

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