but in all seriousness (I've a hatchback)
I keep a big Tupperware box with stuff like jumper cables, some towels, my wheel lock adapters, air compressor, etc...
Fits neatly under the shelf which comes with the HB
i always carry tools in every vehicle i own. cwp holder so, i excersize that priveledge everywhere i drive. in the winter months, i also carry a snowmobile shovel, a blanket, a big bag of trail mix, one bottle of crown (for firestarting purposes when i get stuck overnight. DUH! )
Larson NMO mag mount and a Comet 4.5 foot 2m/440 NMO antenna.
Construction type helmet (2ea), Construction type day glow vest.
A smattering of tools. Windshield shade. Bottled water.
Grocery bags.
Also some stuff.
Back seat head rests (2ea).
Right now only a can of tire inflator/sealer, 1st aid kit and snow brush/ice scraper.
I probably throw in some sort of traction aids because of stock Hankook tires. I've read they will be awful when the road will be covered in white crap.