Keychains as Christmas Ornaments

My mom started collecting keychains whenever we went on a trip (a day trip to a museum or halfway around the world) and using them as Christmas ornaments. They're inexpensive, usually indestructible, and you can pick exactly the ones you like best. You can throw them in your bag without taking up a ton of room while you're traveling, and when you're hanging them all on the tree get to reminisce about the trip it came from and share memories. Best of all it's the kind of thing a kid can get into without spending a ton of money.