Mountain Biking Product Spotlight: MTBR Lights Shine-Off. For years I've recommended the Light & Motion HID lights. They are super bright, but the big drawback has been they don't run that long, so aren't that useful for more than a relatively short bike commute (2 hours at most) and they are heavy at over two pounds. In the last two years though Lithium Ion has made HID lights lighter so a pound is the penalty, but more importantly, LEDs are now so bright, you can get very light, but very bright lights. MTBR did a review and here's the best recommendation from a sort of "ratings":http://www.mtbr.com/reviews/Lights/index_byrating.shtml
* "Jet Lites":http://www.mtbr.com/reviews/Lights/index_J.shtml. Folks seem to uniformly like the Jet Lites products. The Phantom i Single Beam seems really popular. It lasts eight hours by the way. It odes weight two pounds and the 20 watt version lasts four hours, with the 12 watt lasts 6 hours.
* "Light & Motion ARC": . I have three L&M lights now, the old halogen and two HID. They have been great, although I push them so hard, the battery cord are always coming apart.
* "Lupine Edison 10":http://www.mtbr.com/reviews/Lights/product_124905.shtml. For the true maniacs. At $800, it costs more than most bikes, but probably the best and brightest light out there. Metal Halide Xenon Bulb produces 900 lumens and equals a 64 watt halogen bulb. Its 16 watts, weight 720 grams