Point of note: The prices shown for the Nite Rider LED's in an above post are not street prices. I use the Nite Rider MiNewt which puts out about 60 lumens (I forget exactly) which can be now had for about $130US. This is a reasonable (maybe marginal) amount of illumination for commuting at slower speeds (15mph) even on dark bike paths but I will probably upgrade to the MiNewt X2 (150 lumens) for $180US when DST ends. There is also the MiNewt X2 Dual (300 lumens, but only 1:45 hours on high) for about $250US. The dual beams allow broader coverage by aiming one near and one far. I may ultimately spring for these.

These headlights can be made to flash. I have noticed that this is very effective in the daylight hours (or in foggy or rainy conditions) for attracting drivers' attention. Some pedestrians have commented on the high intensity (graphics limitations on this site prevent a detailed illustration of this).

Anyway, I have been very happy with the MiNewt.