What are the black things on the helmets of US troops in Afganistan?  It look like a camera or something.  I have seen it in pictures of troops on CNN and some of the posts here.

You mean NVGs?

NVG Mounts.

Aviator  [img]www.milpubs.com/aviator.gif[/img]

NVG = Night Vision Goggles, just in case you didn't want to ask!  

Any of you notice that some are different than others?

They are mounts for the AN/PVS-7 and AN/PVS-14 night vision equipment.  AN/PVS-14 is a monocular from Litton and the military equivalent to the 6015.  AN/PVS-7 are more common, binocular, single-tube systems.  They're what you saw in Black Hawk Down, fleetingly, on the ground troops.  (Aviators use a dual-tube system to preserve depth perception.)

The mounts on the helmets are the same.  The reason they may look a little different is that there is a small square flat bracket that is up against the helmet.  A swing arm arrangement clips into that little square.  The swing arm allows the soldier or Marine to flip the NVG up out of the way.  The swing arm screws into the AN/PVS-7 or to a little arm to move the monocular in front of the eye (AN/PVS-14).

The reason they may look different is that some units detach the NVG at the swing arm (more common) while others leave the swing arm on the helmet.  

I wonder if the Gen IVs are out in the field yet.