Other than maybe a camera, the two things I never want to travel without are an inexpensive watch and a spork.
I always like having a watch, especially when traveling in different time zones. An inexpensive one is nice because you don’t have to worry too much about it and you can also offer to trade it while bargaining. I got this one for less than $20.
Having a spoon and a fork is great, especially when you end up buying food at a market or grocery store. This one even has a knife built in.