See A Little Light: The official dynamo lighting thread
I just installed a JOS Type T "Dynamobloc" headlamp to the left fork leg on my Centurion. Lucky me, I got it for free when it came through the shop and no one else wanted the poor thing. Well, it languished in my parts bin gathering dust and shopwear until last week, when I realized it had got late and dark on me at the shop and I'd forgot my PB Beamer headlamp. Normally I'd just borrow one of the display models and return it the next day, but we seemed to be temporarily out. So, the dynamobloc. Cleaned it all up, clamped it on, put a new bulb in it and took it out.
ZOMG this has t3h Awsum!! It roXXors my boXXorz!
It is almost silent, just a thin, high-pitched whirr coming off the front tire. And it puts a goodly amount of light right where it will do me the most good. And it seems that it always, always works. I keep a spare bulb taped under my saddle but even though I've screamed down some long downhills-- fast enough to keep up with traffic, say 35-38 MPH, the bulb hasn't blown yet.
I'm a little in love. And the fact that the other retro-grouch at the shop has been pouting that I have one and he doesn't, doesn't hurt a bit.
So whaddaya got? What lights your path?