With warmer temps, running at night is all the more inviting or, at least, finishing a run after the sun sets becomes much more tolerable. Except for one thing: getting caught in the dark and the increased hazards of trail obstacles that poses. Petzl's CORE System ($40) offers USB-compatible, AC/DC rechargeability that runs off of computers, solar panels and wall or car outlets. It clicks into Petzl's TIKKA and ZIPKA headlamps and has the lifespan of 900 alkaline batteries. In addition to the variety of charging sources, the CORE System breaks new ground with its CORTEX software that permits you to customize your headlamp performance in accordance with your specific output needs. The compact lithium ion polymer battery is lighter than standard alkaline batteries and performs better in cold conditions. Princeton Tec's BYTE ($20) is a little powerhouse that will be available in early summer. At a mere 2.25 ounces, the dual-light headlamp packs 30 lumens of light that has one Maxbright LED and one red Ultrabright LED, has high and low mode options and a burn time of up to 360 hours with two AAA batteries