I've been looking at this light:
http://www.amazon.com/gp/product/B00...A2P97M9VQDMS1X
600 lumens is bright. I don't know if it would be too much for a helmet mount.
Here is a 300 lumen one with helmet mount:
http://www.amazon.com/gp/product/B00...ione%20Bicycle
Very Borg.