1) Portable charger for iPads/tables, smart phones, and other devices. My portable charger is awesome! I don't have to look for an outlet to charge my phone now. I can charge my phone as I am walking down the street of a town I am touring. I can charge my phone anywhere without having to be close to an outlet. It charges my phone and iPad. It's compact and light weight enough to fit in my purse or even pocket (depending if the pocket is deep and wide).
See what others have to say about the Lenmar power charger. http://www.amazon.com/Lenmar-PPW66-PowerPort-Wave-6600/dp/B005DTJI7Y
2) Umbrella: Come rain or shine a mini umbrella always has me covered.
3) Flashlight: My small, lightweight, glow-in-the-dark flashlight always accompanies me. I've used it in my staterooms to get up in the middle of the night. I've also used it to investigate an unexpected noise. Should the electricity go out whether I'm on land or sea, I'll be able to see.
4) Walking shoes: I wear closed-toe flats when I am flying. In my recent travels, I've worn my running shoes on travel days. This way the bulky shoes do not take up extra space in my suitcase, and I'm quite comfortable while moving through terminals and different places.
5) Sweater or lightweight jacket: I never know what the temperature might be on a plane, in a conference room, in a theatre or a restaurant/dining room. By dressing in layers and having a small jacket or sweater, I can be comfortable no matter how the temperature rises or falls.
What is something that you "have" to take with you when you travel?