Mine is using the arrow keys to navigate typed text while writing and editing. It helps speed things up, versus having to move your hand to the mouse to navigate.
Use the Up and Down Arrows to move/jump vertically.
Left and Right Arrows to move/jump horizontally.
Combine Left or Right Arrow with Shift to be able to select text. Use Up or Down Arrow with Shift to quickly select whole/nearly whole sections of text.
Combine Control with Left/Right Arrow to jump whole words to more quickly move to where you want to type.
Shift + Tab (also works on Linux)
If you have a mouse with side buttons, you can use the side buttons to go back or go to the next page on browsers
Pressing Alt + F4 on the desktop opens up a dialog asking if you want to shut down, restart, log out, etc. (I think this works on Linux as well)
This, I feel unproductive when I use a mouse without side buttons.