I disagree about the limes -- Goslings is very sweet, as is ginger beer. I was turned on to Dark'n'Stormies years ago in Bermuda where they are said to have originated and are served everywhere, always with the local Barrett's Ginger Beer. (Even in a bind, without ice or refrigeration a few summers back, I enjoyed what we dubbed Dark'n'Warmies). Barrett's is not essential, and I like Goya ginger beer best. But I have two secrets that make my Dark'n'Stormies memorable -- and quick to disappear. First, I add to the bottom of the glass either a sliver of ginger root or a few drops of ginger juice. Next, I shake in one or two drops of habanero sauce (it disappears into the flavor profile with the ginger nicely, and makes the lips tingle). I go heavy on the rum, top off with just a tad of ginger beer and a squeezed lime wedge. This way the soda's sugar doesn't outcompete the rum's inherant sweetness, and the spiciness keeps you sipping.