--I have a Zone VI 8x10, also.
Something to haul it all around in
Film holders -- brush and canned air for cleaning them -- and for brushing off film holders before putting them in the camera.
Darkcloth
Sturdy tripod
I prefer a spot meter
Notebook for keeping notes, pencil
Small screwdriver for loose screws (such as the ones on the sliders that hold the back on). Pocket knife will do.
Lens and lensboard, cable release
Cleaning supplies for lens
Something to keep time with for those long exposures..."one anseladams, twoanseladams..." gets old after a few minutes.