Too much to drag out and show...I carry a tote box containing spare belts, hoses, a PS pressure hose, fuel filter, and extra fluids - oil, coolant, brake, PS, trans. I also have a tool bag with some screwdrivers, pliers hammer and electrical items - wire, connectors, crimper, multi-meter. Spare dist. cap, coil, voltage regulator, ballast resistor, points and condensor in case the 25 yr old Pertronix takes a dump though I recently picked up a spare Pertronix kit. I also have a socket and wrench tool kit in a plastic case, jumper cables and a scissor jack. I usually throw my regular toolbox in the trunk for long, multi-day trips for good measure. Probably a few other things I am forgetting.
Seems like a lot - good thing my car has a big trunk lol, but I've done a fair number of roadside or car show repairs over the years as well as helping others. I have needed most of these items at least once, usually on long trips, and the Boy Scout in me says to "Be Prepared".