The darker sunglasses are, the better they work on the sun, and the worse they work on everything else you're trying to see. Now, the ancient and mystical art of holding your hand up to protect your eyes has been modernized and stuffed into a pair of shades.
Dynamic sunglasses work just like a normal pair of polarized sunglasses, except that they have an extra liquid crystal layer sandwiched inside each lens. A tiny camera in the frame of the glasses watches where the sun is, and then turns on a little square of LCD pixels in between the sun and each of your eyes, shading your retinas. If you move your head, the LCD shade moves with you, making sure to keep the sun nice and dim. Meanwhile, the rest of the glasses are just acting like normal sunglasses, and you can see the rest of the world without any trouble. If necessary, the glasses will even create multiple dynamic LCD shades to help you see through things like reflections and glare.
The company behind all this is called Dynamic Eye, and they've got an actual working prototype of their dynamic sunglasses all ready to go (there's a video of the shades in action here). To start commercial development and production, they're asking for the shockingly low amount of $20,000 through Kickstart, and if you toss in $1,500 of that, you can get your eyes on one of their beta test units to fool around with. Sungazing, here I come.