Most of the close calls that I have heard about and seen personally are electrical in nature. Batteries are relocated with no regard to safety be it the battery and/or the wires. When I attended my first NATS in '01, I got to watch a former syclone owner try to arc weld while staging for a run at night. Had one of his battery cables pinched by the cab and frame... Batteries always give off hydrogen gas which is highly explosive (remember the Hindenberg?) sparkage anywhere near a battery can have dire consequences.
Touching on the hacks that are out there in the mobile electronics, I have seen some down right DANGEROUS installs personally. When troubleshooting my bud's starting problems, I noticed that the place that installed his stereo drilled a hole through the passenger side floorboard to run the power wire to the amp. No problem, just drill a hole the size of the wire and DON'T DEBUR where the drill bit pierced throught the sheet metal and DON'T use a grommet to protect the wire. Afterall that is 110% safe, NO danger there whatsoever...
Those of you who patronize these establishments should be more concerned with inspecting the quality of the install MORE than how your system sounds *initially*. These guys royally piss me off because I have had to make many installs "right" and I do it for free when my friends/family PAID someone to do a job and they did a total hack job :evil:.
Lastly, there is NO reason to not keep a fire extinguisher in your truck at all times. Unless watching your truck go up in flames is an acceptable option.