The new Windows 8 operating system has the usual keyboard shortcuts, just like all the previous versions of Windows did but with extras. The difference is, Windows 8 has such a new interface, that it might be easier to use keyboard shortcuts. For example to shut down Windows 8 there are 4 steps, using a keyboard shortcut there are less steps.
Please Note: If you’re new to keyboard shortcuts, you will need to get very familiar with the Windows key on your keyboard. It is located to the left of the space-bar. So when it says “Windows Key” it means you need to hold that key down and press the other keys required.
Windows Key: Switch between the Start Screen and the desktop.
Windows Key + D: While on the Windows desktop this key combination will clear all the open windows and show the Desktop, a second press of the combination will reopen all the windows previously hidden. If this combination is pressed while on the Windows 8 Start Screen the Windows desktop is displayed.
Windows Key + F:
Brings up the files search menu
Windows Key + W:
Brings up the settings search menu.
Windows Key + Q:
Brings up the application search menu.
Windows Key + L:
Locks the machine.
Windows Key + a Number:
Launches a program from the Taskbar. Windows Key + 1 runs the leftmost program and Windows Key + 0 runs the tenth from the left. If the app is already open, this shortcut will switch to it.
Windows Key + T:
Cycles through items in the taskbar, from left to right. Pressing the return key will then launch the selected application.
Windows Key + Arrow Key:
Perform Aero Snap. The up Arrow maximizes the window. Left Arrow snaps the application to the left half of the screen, The Right Arrow snaps the application it to the right side of the screen, and the Down Arrow minimizes it.
Windows Key + C:
Launch the Charms Bar on the right side of the screen.
Windows Key + X:
Launch the Power User Menu, providing many of the functions lost with the missing Start Menu, such as access to the Control Panel, System, Device Manager and Command Prompt.
Windows Key + Pause / Break:
Open the System window
Windows Key + E:
Launch Windows explorer.
Windows Key + P: Cycle through the second screen projection mode.
Windows Key + I:
To avoid the Charms bar then choosing Settings it’s possible to go directly to Settings. This will reveal the Power button, too.
Windows Key + H:
Used in applications to email or share its content with someone on a social network. The application must support this.
Windows Key + R:
Opens Run menu where you can launch programs by typing in their executable file names.
Windows Key + . (period key): Docks the current Windows 8-style application to the right or left, depending on how many times you hit it.
Windows Key + Z: Doing this combination on the Start Screen will bring up app menu, which shows contextual options for the active app.
Windows Key + PrtScn (Print Screen):
Takes a screenshot and saves it to the pictures folders as a PNG files.
Windows Key + O:
Locks the screen orientation.
Windows Key + Page Up / Page Down:
Doing this combination on the Start Screen will cycle through which display the Start Screen is shown on.
Windows Key + Tab: Brings up the Task Switcher and toggles between Windows 8-style apps, note in Windows 8 this no longer switches between desktop applications.
Alt + Tab: Brings up the Task Switcher and toggles between all applications (Desktop or Windows 8-style).
Alt + Shift + Arrow Key:
Doing this combination on the Start Screen will move the position of an applications shortcut.
Alt + F4:
Shut down the current application.
Source: Tech Hack http://windows.microsoft.com/
Many of these keyboard shortcuts can apply to other versions of Windows but anything to do with the Charm menu only applies to Windows 8.