Everything from Voidtools is a really nice program. It lets you search for any file on your computer and it's really fast. As you type in a string, results will appear. I find it extremely useful because of this. Generally, I try to save files with descriptive names, and with Everything I can pull up a specific image or executable (or whatever) within seconds. You can also click and drag the results onto the window of other open programs, which is also pretty useful.

For example, I can search for a specific file that I want to send to someone when I'm using a messaging program, and I can select the file, and drag it over the window of my messenger, and that way I can attach the file and send it.

On Linux, FSearch works in a similar way, but at least when I used it on XFCE, it didn't have the same slick click-and-drag support that Everything has under Windows.

Winamp is pretty much my endgame of music players on the computer. For me nothing comes close but it obviously comes down to preference. I like it because it's relatively simple, but it has a good amount of features if you ever want to use them.

It has support for key combinations, so you can pause, play, skip, etc. with a key combo.

I think my favorite part of it is the skin support. There are different kinds of skins you can use, but for me, it's the Classic skins that are the best. You can find a ton of old Winamp Classic skins on the Web to download and use. A lot, probably most, are from the 90s and early 2000s which I like.

On Linux I use qmmp because it supports using Winamp skins. I do think there are some other music players that can do that though.

Irfanview is an image viewing program with a good amount of features. You can make adjustments to the image as you are viewing it if you wish, like changing brightness, flipping or rotating, etc. You can also edit the image and save a copy, but I don't generally use this as an image editor. It can be useful sometimes, though. What I like about it is that the display is very simple and unobtrusive, and looks nice when Windows is in Classic mode.

Paint.NET is an image editing program. You can use it like MS Paint to draw normally, but it also has a lot of extra useful features. It supports layers, a lot of effects and distortions, and more. I've used it to make pixel art kind of stuff before. And I think you could use it as a photoshop alternative in some cases.