Dull Men's Club

Go around the house and look at all your outlets. You’ll find that GFCI outlets put out a small amount of heat. (Something to do with their function that is unavoidable.) Regular outlets that are warm and under no load may require investigation.
You can also spot heating conduits in walls, roughly figure out what power adapters are not very efficient, and even use them to gauge how well heated blankets and the like are working. I used mine to look at studs in the wall to figure out (well, be certain about) how some old renovations were handled.

you can sometimes use these as a stud finder, depends on the wall

If you ever do electronics repair and are good at soldering these are a lifesaver for quick diagnosis if the resolution is high enough. Look at the board, apply power, and the part that is shorting out will often quickly get stupid hot. Sometimes it will be a complex repair you can’t easily do like a bga chip but you’d be surprised how often it’s just a random capacitor that went bad in your phone or switch or whatever and swapping it out (or even just getting rid of it if it’s an extra filter) fixes the issue. The hard part is finding out the value bc there are never schematics

A less easy to use alternative to this that I use bc thermal cams are expensive is squirt isopropyl alcohol or flux on the board and apply power. It’ll boil at the point where the part is shorting. Harder to determine but much cheaper. If you already have the camera though

Totally random thought, but check the temp of different things both directly, and also in a mirror reflection. I wonder if it'll sense the same temperature via a mirror reflection...

Coolest thing to look at is running tap water, switch from hot to cold

Balls... First thing I would check LOL

How warm is your empty chair after you've sat in it for an hour

If you have a pet that isnt allowed on the bed but you know she gets on it when you are not there, now you have the tools to get that proof. >=)

And here I am using an IR thermometer like a cave man

Corners of rooms, especially outside corners and wall sections behind furniture and then compare them with the dew point in the room.

https://www.calculator.net/dew-point-calculator.html

If the walls are colder than the dew point, you'll get condensation.