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Duplicate the current tab
If you drag the icon to the left of the URL up into the tab bar, it will open a second tab on the same URL (but without the back history). I find this useful for example when I'm scanning for good google hits. Click a search result; if it's good, drag it up, go back to the first tab and hit back; else just hit back; ...aaand repeat. This allows you to collect the set of useful hits very quickly.