Here are 21 items I suggest bringing with you when you travel (which is something I do a lot of, as a customer service consultant and keynote speaker).
1. Duct tape. Sh*t happens. Duct tape can make it unhappen, at least temporarily.
2. Super glue. When the above-mentioned sh*t hits the fan, super glue can help put together the pieces when it does.
3. Band-Aids. Trust me.
4. Ziploc bags, for all sorts of reasons. Tom Peters (an even more frequent traveler than me) has waxed poetical on the magic of Ziploc bags, and Seth Godin has done the same. They keep you organized, waterproof/spillproof, and you can see what's inside them before you decide whether or not to dig through them.
5. All sorts of extra cables and adapters and batteries.
6. Bose noise-canceling headphones. With these, you don't have to have crank the volume level to an earsplitting level just to rise above an airplane's cabin noise.
7. Disposable earplugs. Lots of them. I use these yellow cylindrical 3M foam ones. Don't let your kids swallow them. Nor your pets.
8. An eye patch so you can sleep when your hotel room's alleged blackout curtains fail to meet in the center, or along the edges, as they generally do.
9. Those Starbucks Via instant coffee packets, so you always have coffee, or some semblance thereof, first thing in the morning even when you're in a strange hotel room with a coffeemaker of questionable provenance and cleanliness. If you like cream you can bring those ultra pasteurized shelf stable half and half minis as well, to avoid leaving yourself at the mercy of the instant creamer nastiness in hotel rooms.)
10. Night light. Hotel rooms are unfamiliar territory. Taking a spill en route to the bathroom or running into one of those stupid glass-topped end tables is no fun.
11. Styptic pen for when you cut yourself shaving. (You know if you're prone to this. I am.)
13 . Chargers and battery backups.
14. Purell wipes. I'm sure you washed your hands this morning, but did everyone who's going to shake your hand later today?
15. Bathing suit and swimming goggles. I like this swimsuit (by Columbia) that is designed to double as shorts, so it is useful whether or not the hotel has a pool.
16. Extras of everything such as contact lenses, that can't be replaced easily on the road.
17. Any medications you take regularly, with enough to spare to last you in the event you get detained on your travels for a couple of extra days.
18. The tools that are specific to your trade. As a keynote speaker I bring, for example, an adaptor (dongle) for my Mac to ensure compatibility with the audiovisual system at events, among many other small but lifesaving items. When I'm consulting, I bring pocket-sized notebooks. And so forth.
19. Business cards. I know some of you think these are pass. You're wrong.
20. Additional identification (even if it's expired, you may be able to use it in a pinch). And a spare credit card. For when your wallet (containing your license and the rest of your credit cards) is lost and you still need to get on your plane
21. Your family, if you're going somewhere fun. They'll appreciate it. (Leave them behind when you're going somewhere dull; they'll appreciate that as well.)