The Economist is skeptical about calculations that English is about to become the first million-word language, because nobody agrees on the criteria. But there seems to be little doubt that it is the world's biggest language, partly due to its complete lack of regulation. So be sure to use it for Good, not Evil.
(Aside: Having the Oxford American College Dictionary and American Thesaurus of Current English ($14.99) on the iPhone is, to this word-worker, itself worth the ridiculous toy's price. No more being all eh, fuck it, I don't really need to know what cunctation and prognathous mean because I can't be arsed to haul out one of the many cumbersome dead-pressed-tree volumes that clutter house and weigh down backpack. Takes me five seconds to look up a word, anywhere I am, and it's totally speeding up my trip through Infinite Jest. (The complete OED is not yet available as an app. Emphasis on yet.))