This is taken from an off-roading forum I am on so a fair amount of it may be geared towards recovery, but there are a few good ideas here. Basic recovery items are also a good idea to have.
Basic recovery and other equipment (MUST HAVE)
To take with on every trip (even day and easy trip) and even for beginners
- Spare key somewhere in or on the truck (more important for more remote trips)
- Fire extinguisher and first aid kit (should always be in the truck)
- Good quality tow strap at least 2"x30'
- At least 2 x D Ring shackles (3/4" Heavy duty, also check recovery points on truck)
- Full size spare, jack, wheelnut wrench, wheel lock "key" and all other tools to swap the spare on your truck, check the tools and spare before you leave.
- Tire pressure gauge with deflator and/or tire deflator(s)
- Small compressor (capable of airing up truck tires) or other way of airing up like CO2
- Communication with other trucks, FRS, CB or HAM pending on group
- Basic hand tools like wrenches, screwdrivers, pliers,
- Duct tape
- Gal or so of water (drinkable in a pinch)
- Trash bags
- Gloves and some rags
- Zip ties in assorted lengths and widths, as well as a few few extra big ones
- Shovel (compact one would be better than nothing in a pinch)
- Flashlight(s) (with spare batteries, ideally add a headlamp as well)
Intermediate recovery and other equipment
When doing moderate difficulty trails and more remote
- Basic kit plus items below
- Additional tow straps preferably 3"x30' and high capacity (see link above)
- Snatch strap of 30' (for mud and bogged down recoveries)
- 1-2 more D rings shacles (3/4")
- For trucks without HD rear bumper, a hitch reciever with recovery shackle mount (like Warn)
- Tire repair kit
- Spare tire valve cores, tool to remove/replace, spare valve caps
- Spare fuses (including the bigger fuses see hardcore below)
- Electrical tape and some isolated electrical wire
- Wire, pliers and sidecutters to tie up components in a pinch
- Hi-lift (especially useful with sliders, also make sure it is properly secured for driving)
- Hi-lift base plate, also a Liftmate (tire), bumper adpater (if ARB) and slider adapter can be handy
- More extensive list of hand tools
- More water
- Bungee cords
- Assortment of bolts and nuts (metric OEM stuff and non metric aftermarket stuff) (Check shock mounts and common other areas like skids, etc)
- Small Digital Volt/Ohm/Amp multimeter
Winch Accesories
- control unit (leave it in the truck or keep in you basic recovery bag, no help if you can use the winch, if you have a remote control, leave it in the truck)
- Tree saver strap
- Snatch block
- Winch line extension cord (optional for long distances)
Hardcore Recovery
- Intermediate kit plus listed below
- Field repair guide (see FSM for critical components copies and TQ settings)
- 2+ HD Jack stands (don't want a to work on a tippy trucl on hi-lifts again)
- Chain with hooks on the ends to tie up axles, etc.
- Ratchet straps for add loose pieces (cargo or truck)
- Loctite blue and red compound
- Loctite locweld or similar liquid metal bond (fast curing needed)
- Gasket maker
- Complete spare front CV axle assembly
- 35MM socket and HD TQ wrench
- Breaker bar, big srewdriver, circlip removal pliers and big hammer
- Spare CV axle circlip (diff side) and diff oil seal
- Spare tie-rod and tie rod end
- Tie-rod and ball joint puller
- Spare Rear driveshaft (tranny to diff)
- Only in very extreme cases spare rear 3rd and sideshafts (leadfoot rockhopping)
- Spare relays for Starter, EFI, ABS SOL, Fuel pump, Headlamps, Ignition, Power relay (will get part #s, see attached relayloc pdf)
- Spare HD fuses 140A altenator and assortment of HD 30,40 and 50A fuses. (mentioned again)
- Spare rear shocks (only if you don't have HD remote res or monotube shocks) and fitting hardware (includign OEM bolts) (Only for heavy load long distance, remote trips)
- Spare brake lines (front and rear)
- Brake fluid 2-4 small botttles
- Diff fluid 3 Qts or more
- Tranny fluid 3-4 Qts
- Engine Oil 5-6 Qts
- Wheel bearing type grease
- Trail cleanup kit for oil spills, etc
- Oil drain catcher
- Small gas soldering iron with solder (or 12V or 110V if you have an inverter)
- Hand cleaner, lots of spare rags, latex or rubber gloves (if you dont like the smell of grease and oil)
- Extensive set of hand tools, including wrenches and socket sets, screwdrivers, adjustabel wrenches and vice grips, pliers, side cutter, longnose pliers, knifes.
- Impact wrench can be handy with regulated CO2