Kanata might be the most useful tool I can't find a use for.
It's a cross-platform keyboard mapper. Some cool features:
git commit -m"Experimenting" [ENTER]. Ctrl + M, then Down, can reduce the music volume by 10%.... and there's lots more.
Unfortunately, I have not been able to find a single use in practice. My main bottleneck is that I don't remember the shortcuts. So, instead, I use rofi.
Rofi is a programmable menu launcher. The great thing is that I don't need to remember stuff. When I map it to keyboard shortcuts, it pops up a menu and I pick what I need.
I use it to:
#1: Open any file or browser tab with Ctrl + Alt + F.
This is my most used shortcut. It replaces Everything for files, and Chrome Search Tab with a single shortcut.

#2: Paste any prompt fragment with Ctrl + Alt + P.
This is especially useful when adding a prompt fragment, like Expert Lens in the middle of a prompt, or analyzing call recordings a dozen times a day.

#3: Edit the clipboard with Ctrl + Alt + M (for Markdown).
This is a killer feature. I often use it to:

I'm still keen to find a use for Kanata, but for now, my use of Rofi will continue to grow.