win or alt+f1

Open the Overview, showing all workspaces and windows.

alt+tab

Cycle through open windows. Add shift to cycle in the reverse direction.

alt+`

Cycle through open windows of a single application (while alt+tab switcher is open).

alt+esc

Cycle through open windows without invoking the alt+tab switcher.

alt+f6

Cycle through open windows of a single application without invoking the alt+tab switcher

ctrl+alt+arrow up/arrow down

Move to workspace up/down

ctrl+alt+shift+arrow up/arrow down

Move current window to workspace up/down

alt+f2

Open a command dialog box.

alt

Hold alt while selecting the "Suspend" item in the user menu (upper right) to display the "Shut Down" option.

ctrl+alt+l

Lock screen.

ctrl+alt+delete

Logout.

printscreen

Take a screenshot of the current view.

alt+printscreen

Take a screenshot of the current window.

ctrl+alt+shift+r

Begin recording a screencast. (may not be supported in all distributions)

alt+f4

Close current window.

alt+f5

Restore/Unmaximize current window (if maximized)

alt+f7 or alt+drag

Move current window. Use mouse or arrow keys to move, then press any key or click the mouse to finish.

alt+f8 or alt+middle click drag

Resize current window. Use mouse or arrow up/arrow down to resize, then press any key or click the mouse to finish.

alt+f10

Maximize/Unmaximize window.

alt+space

Open the window menu.