Julbo Trek glasses make it into my personal "All Time Great" list of backcountry skiing accessories. They feature the Spectron 4 lens, which is roughly twice as dark as any of the other sunglasses out there, which makes it perfect for bright, white snow.
The frames are strong, yet flexible and take an amazing beating. I also like how you can add or remove the side wings to increase ventilation.
To me, this glasses are kind of like a half goggle, half sunglass, which makes them perfect for all around activities.