A bottle opener shaped like a key so it fits neatly between my other keys on my keychain. I thought I lost my keys once and I was way more upset about that than my actual keys, despite it probably being pretty easy to find on Amazon.

An extention cord thingy.
I got it in some cheap chinese goods place so i thik it was like 15€.
It was an impulsive purchase (i am the type to get tools impulsivly)
But for a long time it was a useless dust catcher.
After i moved there finally where oppertunities for it.
So at that point it got unexpectedly useful.

For summer i reccommend buying a hand fan + a spray bottle (spray water on skin & use fan, its really nice)

Even though I don't regularly use it, I'm glad I have a p38 can opener on my keychain. Just in case I end up in a survival situation, it's good to have alongside a good keychain bottle opener. Obviously not as good as a leatherman, but for under $20, yeah, these two are worth it.

A back scratcher. Got a pack of 4 for a few bucks after one I was gifted broke. I'm old and have one quite arthritic shoulder, so half of my own back is unreachable. It's especially shitful getting an itchy back at night, but now I don't need to get up to relieve it. I use it every day, and every day I bless the person who first gifted me one.

I have a little fold-out rack with (I think) 24 individual clips on that hold socks and other small items. It can then be attached to the washing line, taking up a lot less space than hanging things along the length of it.

It was £3.99 and it makes putting the washing out so much easier. I much prefer to line dry things outside than using the dryer when I can.

This under US$5 milk frother from Ikea. Froth up milk, pour the coffee in, so nice.