Wow. This is some cool stuff. I have been all about upgraded lighting in my car (bought the european versions, added a large wiring and relays, then put in 90/100watt Philips Rallye H4's), and now that I have a road bike I want some lighting for it.
Since I'm on a tight budget I not about to buy one of those kits already made, or stick myself with some cheap low output "headlight" such as some of the weak LED and oldschool Cat Eye stuff(HL-500). I bought one of those flashing LED tail lights for safety and for my headlight I have been messing with different ways of mounting my Surefire 6P flashlight to my bars. I like it because it is bright, and very versatile. I have the main body with the bright halogen bulb, along with an extension that allows me to use a rechargeable nickel cadmium battery opposed to two(expensive) CR123 Li-Ion batteries. Also for christmas I got a Luxeon 1 watt LED head for it. Honestly the output of this LED is pretty amazing. Though purplish light, it is brighter than your run of the mill large D cell MAG light in the flood pattern(the MAG when focused has more distance). Either way I already own the light, so I just mounted it up to my bike. I went to home depot first and got some plastic tips for a stool, cut out the bottoms and used them as sort of protector/spacer shims. then i used a clamp to hold the light with these "shims" onto the stem of my bike. tried it at dusk, it was decent, but I'm charging the Ni-Cad and going to put the halogen head back on it and take it for a ride tomorrow(hopefully it will not be raining).
check this site out, they have some serious flashlights, these 1/3/5 watt Luxeon LED's are so much brighter than the stuff you are used to you would be amazed, plus this guy sells the parts, so you can make your own flashlight/bike light for a small amount of money.
http://elektrolumens.com/