I picked up an LED headlamp two years ago on a ~$13.00 whim. It's the size of a walnut, weighs an ounce, has three brightness settings+.... it's a wonderful thing. My only complaint is to reduce brightness it's basically a strobe light. Not real noticeable but the first time in the rain kinda freaked me out.

I use it rather often at home and it seems the original batteries are still hanging in there. Do LEDs dim with old batteries or do they just die. Somehow I expect new batteries will cost more than a new (batteries included) headlamp.