CREE XR-E LEDs and optics are readily available if you're into homebrewing lights. I just picked up a few and will be putting together a helmet mounted light over the next week or so.

I got Q2 bin which should be good for 180 lumens at 1000ma (3 watts) each, for a total of 540 lumens minus 5% - 10% loss through the optics so lets say 500 lumens wherever the helmet is pointing

They're driven in series with a Buckpuck and drop 3.7v at 1000ma each (11.1v total). I'll be running them with a 13.2v (12v nominal) 3500mAh SLA at first but I'm looking at Li-Ion or Li-Po options. The optics are 2 x 6 degree and one 15 degree.