ITT: interesting but useless magical items.

I'll start...

>boots of freezing
Wearer will always be cold
>sandals of heating
Wearer will always be hot
>umbrella of raining
User will always be rained on
>butter knife of buttering
Toast can always be buttered without any actual butter if this knife is used
>bottle of refilling
Water can be poured out of this bottle into a lake or large body of water, however whenever a person drinks from it there is no water inside
>neverburning torch
Torch cannot be lit and puts out all flames within a typical light radius of a lit torch
>foggy binoculars
Binoculars that only work when a fog is present
>magically over-sized belt
No matter the size of the user, the belt is always too big and there are no notches smaller than over-sized
>visibility cloak
All characters know your position within 5km