Click and hold the “Later” button in a notification for additional snooze options.
Click the Notification Center menubar icon while holding down the Option key to toggle “Do Not Disturb”.
Start writing the name of a file or directory in Finder to select it.
Press Tab and Shift+Tab to select the next and previous match.
Do a three-finger tap on a file in Finder to preview it in Quick Look.
Same to close it. You can also press Space.
Resize a window while holding down the Option key to resize from the center.
Press Shift to keep the aspect ratio. Press both keys to do both.
Press the Option key in a file context menu to get the ability to copy the path of the file.
For plain text destinations like the terminal, you can also press Cmd+C with the file selected and then Cmd+V in the terminal to paste the file path.
Move a file by pressing Cmd+C and then Cmd+Option+V in the destination directory.
Do a three-finger tap on a word to view its definition.
You can also press Ctrl+Cmd+D or force tap if you have Force Touch.
Insert an emoji anywhere by pressing Ctrl+Cmd+Space.
In Finder, press Shift+Cmd+. to toggle hidden files.
Works in the Open and Save dialog too.
Rearrange menubar items by dragging one while pressing the Cmd key.
Hide rarely used menubar items with the Bartender app (paid).