Creative Item Ideas

This has probably come up somewhere but I am keen to hear your guys creative or interesting items you gave your players. I think there is a lot you can do but sometimes I get stuck in my head when thinking of cool items that are not just overpowered.

I go first: a magic music sheet that when played has a certain effect (in my case a "sonata of the forgotten", effect is pretty campaign specific) unslippable shoes, glowing chalk you can use to mark smth for example in a labyrinth and a mirror that makes invisible things visible