I have been using a nitrider minewt for my commutting bike/ running, for the last 2 yrs, granted not the brightest, but for road stuff it is more than adequate, the occassional sortie offroad (canal paths etc) it is fine (not good enough for full on offroad mtb), helmet or bar mount, super light, i also use it for running as well and never notice it really.
usb charge at work off the computer means i never have to worry about it running out, lasts over 2 hours. job done.
think i paid around £60 for it in a sale from lbs.