Most of you agreed with me that blue-tinted "weight-loss" sunglasses seem ridiculous. But colored lenses can be beneficial, and I'm not just talking about rose-colored glasses. Bolle makes a very cool line of Competivision Sunglasses for tennis, which use blue-tinted lenses to mute every color but yellow. That way, everything looks somewhat duller except the bright yellow of the tennis ball, allowing you to keep your eye on it better.
I don't personally own a pair of these, but I have tried out a friend's pair, and I can say that they really work, especially when it's really bright or sort of hazy outside. The lenses are available for a number of different frame styles, which range in price from about $55 to $90. Bolle also makes a similar product for golfing. If you've tried either of these, I'd love to know what you thought.