Windows 8 Shortcut Keys

Windows logo key+spacebar Switch input language and keyboard layout
Windows logo key+O Locks device orientation
Windows logo key+Y Temporarily peeks at the desktop
Windows logo key+V Cycles through toasts
Windows logo key+Shift+V Cycles through toasts in reverse order
Windows logo key+Enter Launches Narrator
Windows logo key+PgUp Moves Metro style apps to the monitor on the left 

Windows 8 Toggle Option

Windows logo key+PgDown Moves Metro style apps to the monitor on the right
Windows logo key+Shift+. Moves the gutter to the left (snaps an application)
Windows logo key+. Moves the gutter to the right (snaps an application)
Windows logo key+C Opens Charms bar
Windows logo key+I Opens Settings charm
Windows logo key+K Opens Connect charm
Windows logo key+H Opens Share charm
Windows logo key+Q Opens Search pane
Windows logo key+W Opens Settings Search app
Windows logo key+F Opens File Search app
Windows logo key+Tab Cycles through Metro style apps
Windows logo key+Shift+Tab Cycles through Metro style apps in reverse order
Windows logo key+Ctrl+Tab Cycles through Metro style apps and snaps them as they are cycled
Windows logo key+Z Opens App Bar