Don't get caught in the dark without the M-Wave® 3-LED headlight. This battery-powered device attaches to your bike's handlebars with an included clip.
I've gathered from reviews and experience that bike headlights tend to have two problems. First, they don't have enough power, and second, the mountings aren't tight enough or strong enough. This light (my second) is fine on both counts. The mounting can be a bit loose on small handle bars, but it's not too bad. The beam is bright enough so that the light can be adjusted to shine 40-50 feet away and still be useful. Whatever you do, don't buy the lights in the $10 and below range, the mountings snap right off.