Busch und Muller Ixon IQ Speed LED headlight set

This light is a revelation. It uses just one LED, but produces the most amazing, bright light I've had the pleasure of using. I have just one in the front of my Mango velomobile, and have been able to see where I'm going at 40 km/h in complete darkness. The key to its effectiveness is not merely the high output of the LED, but the optics. Instead of spraying the 50 Lux light everywhere, including where it isn't needed and dazzling oncoming traffic, a combined reflector and lens produces a shaped beam, with more light at a further distance, but a very sharp cut-off at the top. The result is that this lights the road in front remarkably well without dazzling oncoming traffic.

It's not cheap, but if you have a long commute in the dark there is little, if anything, else to compare. It works much better than any other bike light I've ever used.

This is the full set of one headlight with a battery and charger. It can be used together with a second headlight for a two light setup.

2011 note: This is still a very nice light, and I'm still using mine. However, the new 80 lux Philips light is brighter, has an even better beam pattern, and is cheaper so you may want to consider that one instead.