For those focused on a good helmet mount, look at the zefal doodad plus. This is normally used to mount a bike pump but works great as a helmet light mount.. The twofish bike block - it has parallel mounting is a good one too.. I found that the mount you use is different for each type of helmet, so it is best to try a couple different models and see what works best.

http://www.amazon.com/Zefal-Doodad-P...6311753&sr=1-1
http://www.amazon.com/Two-Fish-Block...6311719&sr=8-1