Tyre plug kit.
Water.
Mesh for radiator cover.
Water.
Enough tools (and the correct ones) to tighten anything that can (and it will!) rattle loose.
Water.
Metal mend (the 2 part stuff) to fix a holed fuel tank. Also the plasic putty stuff for water tanks, jerries etc.
Water.
A few coat hangers. The metal ones. Can be used to re-attach an exhaust and can double as a spinefex remover for under the vehicle.
Water.
A sharp knife. Sounds disgusting, but to dispatch any animal strikes that arn't finished off.
Did I mention Water...........
Tyre pressure gauge and deflators.
Oh, don't forget the Water............