Paste without formatting

Command + Shift + V

Reveal desktop

Cmd + F3

Create new directory

(If the parent directory is too full there's nowhere to right click)

Cmd + Shift + N

Switch between two windows of the same app

Command + `

Show/hide hidden folders

Command + Shift + .

Change default column width

Alt (aka Option, ⌥) + Drag Width

Change default app

RCDefault lets you change the default application by e.g. file extension. When you install, it gets added to your system preferences panel

Add custom app shortcuts

Mac Shortcuts