Light sticks have pretty limited utility but I keep some around. They're cool and nonflammable so they can't start a fire. They don't need batteries and they keep for quite a while. On the other hand their output is low and the "burn time" is short(ish) depending on your POV. They're inexpensive enough and compact enough that I keep some for the limited range of things they work well for (mostly camping for use as markers).
“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman