In the outdoor world, headlights are one of the most useful pieces of gear around. They let you read comfortably, mess with cookware at night, find your way over a narrow pathall while keeping the hands free for more important things than holding a flashlight. Of course, LED-style headlamps are the hot item right now, with their surprising brightness and astonishing run-times of up to 12 hours on one set of batteries. A good example of this style of light: the Petzl Tikka Plus ($32; www.petzl.com).
I've found LED-style lights to be terrific around camp. But, for the most part they aren't quite bright enough for use on the trail. That's gonna change pretty soon. I've seen samples of new focused-beam headlamps that may prove to be great for trail use. For the time being, though, nothing beats a halogen-style bulb. That's what the Black Diamond Gemini ($39; www.bdel.com) uses. (Well, technically it's a Xenon bulb.) And, it also has two LED bulbs for low-power use when the task at hand is not terribly light intensive. Petzl's Duo ($65) uses the same principle, but with three LED bulbs.
Anyway, either would work extremely well. The Duo uses four batteries for a little longer lighting time than the Gemini, but of course that also adds some weight. See if you can compare the two side by side, then make your final decision.