Aside from the normal things necessary for a show, like a canopy, and print bins, there are other not so obvious items that can be a big help on those occasions when you really need them.
Make a list so that the next time you are packing for a show you don't forget anything. And, if you think of something that you want while you are at a show, write it down on one of your index cards and put it with your money so you remember it for next time.
Index cards - Great for writing makeshift signs or making notes to yourself.
Post-its - For notes to yourself or emergency price tags.
Scissors - For cutting papers or if you can't find your wire cutters to cut the tie wraps. And if you're really bored, you can make paper dolls.
Stapler & extra staples - Good for emergency repairs of tarps and other things.
Tape - Duct tape is another great emergency supply with lots of uses.
Multipurpose tool - A Leatherman or Swiss Army knife is a great thing to have to handle most any situation where you would need a tool. Plus it doesn't take up much space.
Advil - You never know when you're going to get a headache
Imodium or Pepto-Bismol - Just in case.
Toilet paper - By the end of a show, the portapotties may be out.
Cell phone (fully charged!) - Forgetting your cell phone is like forgetting to get dressed in the morning!
Change of clothes - You never know what the weather is going to be like. It is a good idea to have a full range of clothing so you stay comfortable throughout the day.
Handi-wipes or paper towels - Great if you are a messy eater or if some kid smears ice cream all over everything.
Lunch and Snack food - You never know what sort of food items will be available at a show. It's a good idea to bring something with you just in case. Plus it's a lot cheaper.
Spare car key - If you've ever locked yourself out of your car you'll understand why you should carry a spare key. Locking yourself out at a show is really bad. And, yes, I've seen it happen.
Sunglasses - If it's an outdoor show, your eyes can get really tired from being in the bright light.
Hat and sunscreen - You don't want to go home sunburned!
Water - Keep yourself hydrated throughout the day.
Work gloves - Wearing gloves while setting up and tearing down prevents all those little cuts and scrapes.
Flashlight - In case you're setting up or tearing down in the dark. Or, for an indoor show, in case of power failure.
Bungee cords - You never know when you might need to hold something down.
Fan - A small battery powered fan (or even an old fashioned folding fan) can really help on those hot days.
Umbrella - In case of rain.
If you have any other "must haves" in your show kit, please share them in a comment.