I was typing something and accidentally hit two keys that were side-by-side at the same time, and the text for the last word I was typing was selected. If it's a URL in the Safari address bar, when my cursor is in there somewhere, single tapping two keys at the same time selects any text that's between punctuation. Double tapping two keys selects the whole URL. If this is well known, I apologize. If not, try it out and post your experience. It would be cool if there were also hidden copy and paste shortcuts.