Always in the rig, or mounted on it:
fire extinguisher
Warn xd9000
MagLites (2) w/spare batteries
first aid kit
jerrycan with gas
knife
vehicle safety kit w/flares, space blankets, etc.
For the usual backcountry trip, I'll add:
tool kit
spare battery
spare belts
oil
washer fluid
chainsaw w/gas
gloves
bungie cords
nylon rope
20' of chain w/clevis hooks
15,000lb tow strap
rags
TP (actually, this never really leaves the rig!)
sleeping bag
MREs, snacks, and water
snatch block
Sig P229
During hunting season I'll have my hunting gear, along with a 20- and a 16-gauge with plenty of ammo. For backcountry snowboarding I'll have my boards and gear, plus some extra cold weather survival stuff: warmer bag, four-season tent, camp stove, etc.