Hamish here are a few pictures from the web sight
the link in my signature is from the Marine Corps Pipe Band and the Kilts they wear are a take off the Marine Dress Blue Trouser the Red stripe down the side is called a Blood stripe
it is only worn by NCO (Non-Commissioned Officers) and Officers.(look at bottom picture to see the trouser leg.)


is what the tartan looks like
the tartan is registered and is refered to as
"Leatherneck, US Marine" most places i have seen it. It is one of the American Military Tartans so it is not a traditional one from the view of being a clan or something.
Leatherneck is the Nick name Given to US Marines for the stiff leather collars that were worn during the early days.
here is a picture of the tartan in the shape of a Kilt

and here is the same tartan pleated to the stripe

The home sight is
http://www.alexismalcolmkilts.bigstep.com/homepage.html