Option--space

Opens Spotlight window

→, ←

Expands or collapses a selected folder in list view

Option-→

Expands a folder in a list view and all folders inside it

Option-←

Collapses a folder and all folders inside it

-↑

Opens parent folder

Shift-Option--↑

Selects the desktop

-↓ (or -O)

Opens the selected icon

Option-click the flippy triangle

Expands or collapses all folders within that window

Tab

Selects next icon alphabetically

Shift-Tab

Selects previous icon alphabetically

space bar

Opens Quick Look preview of highlighted icon(s)

space bar

During a spring-loaded folder drag, opens the disk or folder under the mouse immediately

Option-click Zoom button

Enlarges the window to full screen

Option-click Close button

Closes all Finder windows

Option-click Minimize button

Minimizes all windows (works in most apps)

-drag an icon

Moves it into, or out of, the System folder (administrator password required)

Option

Changes Quick Look button to Slideshow button

-drag

Rearranges or removes menulets or toolbar icons

-click window title

Opens a pop-up menu showing the folder path