I got a carbonization machine. I've been drinking way more water these days. I always thought I liked soda because of the sugar. Actually I liked the fizziness. It gets fizzier than anything else I've ever drank.

A bit on the costly stuff but I find the vacuum cleaner robot (not sure it's called this in English) very useful. The house is cleaner to be vacuumed every day (even if it's not as efficient as manual vacuuming or cleaning). Especially with pets and children.

Safe Cut Can Opener, traditional can openers should be extinct. It unrolls the original seal so there's no sharp edges. It also doesn't leave a lip, so none of the insides get stuck on the ledge. Then, if you don't use all the can, just plop the lid back on and throw it in the fridge.

If you like boiled eggs, you need a boiled egg timer.

It's a clear "egg" made of heat-tolerant plastic with a color-changing temperature gauge visible inside. You throw it into the pot when boiling eggs and it lets you know when the eggs are soft boiled, medium boiled, or hard boiled. It's very readable even in boiling water, and the results are always perfectly accurate. These things are totally worth the few dollars they cost.

I got a set of metal picks from Harbor Freight for like 3 bucks. They're similar to the pick tool that a dental hygienist uses. I use these things nearly every day to scrape stuff out of a crevice, retrieve something out of a narrow hole, pull stuff out of a tube or straw, precision clean corners of things, etc. I love them.

A night light that turns on automatically as it gets dark. No more stumbling around when I have to pee in the middle of the night.

Air fryers!

The idea of getting something before I know its usefulness confuses me. Do you mean finding that something is more useful than you expected?

If that's the case, I once had an alarm clock which curiously had a thermometer in it to measure the temperature in the room. I was able to use it - for years - to hold my landlord to account for being shitty on the heat during the winter.

Seriously the most useful thing I ever bought for around the house is barely even a gadget. It's literally just a screwdriver where you can flip the tips and the shaft so that it has four tip sizes; two Phillips and two flatheads. Oh and also a tape measure. That tape measure will save you literally all of the headaches when it comes to purchasing furniture. A good socket set of Allen wrenches for assembling set furniture too.

InstaPot. I hate gadgets and things that have limited purpose so when this was gifted to me I planned to regift it. I use it so often I got an upgrade model. Totally worth the counter space!

Bamboo tongs for taking hot things out of the toaster. They even have magnet built into the handle so I just stick it on the side of my fridge when not in use.

I have a few motion activated lights in my house and really love how convenient those are. One is an in wall light switch and another is a screw in one in a ceiling light socket.

I also use my pour over coffee set daily. And my coffee grinder.

I bought a cheap little wire cutter and keep it in my junk drawer. Great for cutting zip ties and twist ties on packaging.

I keep a water bottle in the fridge. Always have cold water and hardly use glasses. Bring it to the table when you eat.

Lazy Susan on the dining room table for salt, pepper, toothpicks, pencils, sticky notes, etc.

Long plastic dollar store shoehorn by the door.

I get big packs of 3M clean removal hooks from Costco and use them all over the house to hang keys, pants, hats, string lights, jackets, etc.

I bought a variety pack of scouring pads and brushes that I can attach to my cordless drill. Super handy for cleaning stuff that would otherwise take some major elbow grease. Probably bad for my drill, but it's worth it to me.

Extendo arm. It's goofy as hell but it's a god send when there's a bunch of random crap on the floor. They also have deceivingly good grip strength too.

Hand held vacuum. I don't think this is that niche anymore but it works really well for cleaning tables, random tight corners and I park it next to my clothes dryer to easily clean the filter. I also use it a TON for sucking up bugs. Buy a corded one since battery operated ones die fast (I went through 2 or 3 of these personally)

Bench scraper. Easily removes 90% of any grime on hard surfaces. Honestly more effective than a rag and detergent. When I bought mine I decided to try it out on my "thoroughly cleaned" kitchen counter and removed a disheartening amount of grime. Afterwards I use some detergent just to sterilize everything.

A Moka pot, it’s the best coffee I’ve tasted, I’ll never go back to using those coffee machines with the basket and the glass carafe.

Also, a really good chef’s knife, kept really sharp. I use a couple of Global ones.

A good pair of titanium scissors. They aren't very expensive, but cut things far better than cheap scissors. They last a lot longer, too; I've had mine for a few years, and they're still sharp enough to cut my skin if I get a little carefree. I got a two-pack and keep a pair with my lunch box for foodstuffs I need to open at work. I even carried a pair around at work for a while when I needed them to cut zip ties, shrink wrap, and banding.

Had a rice cooker in my kitchen for years because my brother brought it. Never really made use of it until I got my second dog because it became super cost effective to make their food, and a big part of it is brown rice.

A quality knife sharpening system. It'll change your life. Keep your knives razor sharp at all times with minimal effort, and all of your cutting experiences will be far better.

I bought a small rice cooker a while back. I have pancakes way more often now, which has really helped cut down my breakfast budget. I can snag a month of breakfast for like 5 dollars. Yeah sure, they're extra thicc and not as nutritious as a full complex meal, but its a lot less of a hassle than actually heating up the skillet and cooking a meal while I'm half-asleep.

I've been loving the spider skimmer my wife got me for christmas.

Kitchen torch is pretty fun and satisfying for roasting veggies and such

Battery powered handheld vacuum cleaner. Though I'd only use it for bits and bobs and still use the big Dyson for most of the cleaning, but the hand vac gets used a lot more. Also, a spot cleaner for carpets/upholstery. I did expect it to be useful, and it means we no longer periodically hire a rug doctor, but i hadn't appreciated how useful a wet vac is for spills, not to mention the time the dishwasher drain pump failed and I didn't have to mess around bailing it out.

I bought a griddle scraper thinking it was only for cleaning but it's become one of my main cooking utensils

I think my 11 year old was the most surprising.

It wasn't a gadget, but we put a grocery bag dispenser on our wedding registry. We ended up getting it, and it was nice to have a good place to put them that was easy to grab them out as needed. Haven't used it nearly as much now that we are using reusable grocery bags, but it's still nice when I need to put a bag in my office trash can.