theres a thread on here for what to bring on an official naxja run which about covers it all. search for it.
it also depends on how well setup your jeep is. if your rig is a POS then youll need alot more than the usual
this is what i usaully have:
at least 4 driveshaft u joints(ever have to rebuild a blown up rear CV driveshaft on the slabs at 2am with one flashlight and you keep losing needles, its nice to have extras...mike1331 knows what this is like)
rear driveshaft
front driveshaft
vacuum line
fuel line
brake line
various fittings
1 motor mount
plumbers tape
tie rod or 2
drag link
steering box bolts
brake pads (only 2 of them)
o2 sensor
TPS
CPS
fuel injectors
all suspension bolts
random bolts
various vacuum line fittings and brass fittings for fuel line
heater hose
good sized tube of RTV
metal epoxy stuff for sealing a radiator or gas tank or oil pan etc
spark plug(s)
duct tape
electrical tape
10 ft of wire
other sensors you can think of taking a crap on you
i once carried a steering box on the con(wasnt for me though)
1-2 complete sets of spare front shafts(inners,outers, joints)
extra unit bearing bolts
extra caliper bolts
spare rear shafts
2 unit bearings
alternator
dexIII(can be used in tranny, t case, or Power steering)
20w-50 motor (can be used in motor or in Diffs in a bind)
brake fluid
couple extra gallons of water (for radiator or you can drink it)
carb cleaner
grease
jumper cables
hi lift
small piece of plywood
welding rod
welding gloves
small bottle of orange hand cleaner
extra beer and whiskey and food in case you break down real bad for few days and gotta wait for parts etc....
thats all i can think of off the top of my head, im sure i have more crap in jeep for most trail runs
tons of tools
including some odd balls like 3ft pry bar, TRE puller, 36mm socket, puller kit, 3 pound sledge, and much more,
i second the safety stuff and the wag bag and the spill kit