I use an NVG compatible mike lite (white). I have found that the NVG green LED lights are just to dim.
When I flew 2 pilot IFR, we wore the white/red lights that tilt down that are mounted to an elastic headband- by far the best thing I ever used when I was the PNF. I got it at Walmart for about $5 US. When I switched to flying with a helmet, I tossed the elastic headband and put some velcro on the back of the light, then stuck it to the side of my helmet- if I need it I just fold it down.
For walk around, I use a generic version of the surefire.