Update June 2013: These exist!
Years ago I had an idea for “reverse” glasses. All they would do is invert horizontally–or flop–the image your retinas receive as if you were viewing through a mirror. I suspect after a brief period of adjustment you’d be able to function fairly normally wearing them, but your common surroundings would appear oddly different, like the first day waking up in a house with a reversed floor plan.
Asymmetrical skateboarding spots limit your trick options because, as a skater–even if you’re great at skating switchstance–you’re either regular or goofy foot. If there’s only one obvious direction to hit something from, you kind of lose half the available tricks to try on it. Flopped glasses couldn’t switch your natural skating stance, but they would let you see every spot as having a flopped equivalent, which is where the game developers come in.
Every 2 or 3-dimensional game should have a “flop map” option, which would flop the player’s map (but not the controls). This would be fairly trivial for the developer, but would give players double the (perceived) number of unique maps to play on. Obviously this is only interesting on asymmetrical maps like a city or a famous golf course–flopping most sport courts/fields wouldn’t have any real effect.
Another feature of the glasses: They would “correct” what you see in mirrors to be exactly what the world sees–parted hair/crooked teeth/wristwatch on the opposite side. Weird and awesome.