Most Useful Hotkeys for windows 8

Win : switch between the Start screen and the last-running Windows 8 app
Win + C : displays the Charms: the Settings, Devices, Share and Search options
Win + D : launches the desktop
Win + E : launches Explorer
Win + F : opens the File Search pane
Win + H : opens the Share pane
Win + I : opens Settings
Win + K : opens the Devices pane
Win + L : locks your PC
Win + M : minimises the current Explorer or Internet Explorer window (works in the full-screen IE, too)Win + O : toggles device orientation lock on and off
Win + P : switch your display to a second display or projector
Win + Q : open the App Search pane
Win + R : opens the Run box
Win + U : open the Ease of Access Centre
Win + V : cycle through toasts (notifications)
Win + W : search your system settings (type POWER for links to all power-related options, say)
Win + X : displays a text menu of useful Windows tools and applets
Win + Z : displays the right-click context menu when in a full-screen app
Win + + : launch Magnifier and zoom in
Win + – : zoom out
Win + , : Aero peek at the desktop
Win + Enter : launch Narrator
Win + PgUp : move the current screen to the left-hand monitor
Win + PgDn : move the current screen to the right-hand monitor
Win + PrtSc : capture the current screen and save it to your Pictures folder
Win + Tab : switch between running apps
On Tablet:
To take a screenshot on a Windows 8 tablet, simultaneously press the Windows button and the volume-down button on the tablet chassis.