WINKEY
Pressing the Windows  key  alone will open Start.

WINKEY +  F1
Opens the Microsoft  Windows help and support center.

WINKEY +  F3
Opens the Advanced find  window in Microsoft Outlook.

WINKEY + D 
Brings the desktop to the  top of all other windows.

WINKEY +  M
Minimizes all  windows.

WINKEY + SHIFT +  M 
Undo the minimize done  by  WINKEY + M and WINKEY + D.

WINKEY +  E 
Open Microsoft  Explorer.

WINKEY +  Tab
Cycle through open  programs through the taskbar.

WINKEY + F
Display the Windows Search  / Find feature.

WINKEY + CTRL + F 
 Display the search for computers window.

WINKEY +  F1
Display the Microsoft   Windows help.

WINKEY + R
Open the run  window.

WINKEY + Pause / Break  key
Open the system properties  window.

WINKEY + U
Open Utility Manager.

WINKEY +  L
Lock the computer (Windows  XP and above only).

WINKEY +  P
Quickly change between monitor display types. (Windows 7 only)

WINKEY + LEFT ARROW
Shrinks the window to 1/2  screen on the left side for side by side viewing. (Windows 7 only)

WINKEY + RIGHT  ARROW
Shrinks the window to 1/2 screen on the right side for side by side viewing. (Windows 7 only)

WINKEY + UP   ARROW
When in the side by  side  viewing mode, this shortcut takes the screen back to full size. (Windows 7 only)

WINKEY + DOWN  ARROW
Minimizes the screen.  
Also, when in the side by side viewing mode, this shortcut takes the screen  back  to a minimized size. (Windows 7 only)