I just tested a new light, Cygolite 400 usb, flashing before sunset, then on high for ride home.
Plenty of light, plus mounting options.

http://www.amazon.com/CygoLite-Expil...0373263&sr=8-1

Got this tail light, works great.
http://www.amazon.com/Portland-Desig...bxgy_sg_text_b