Something that NO kit is complete without::
TOILET PAPER!!! Works well on leaks, spills, dirty hands, dirty butts, and many others!!
A few others would be gloves, electrical tape, tow strap, and a hammer...
T. Wilbanks,
I forgot the towels... I keep a bucket of scrubs in each truck, and napkins in the glove box.
If you haven't tried the scrubs, you ought to. They are a bit spendy, but sure work well.
curdog87,
I hadn't considered a blue torch. What are some scenarios that you have needed on for?