New OS from Microsoft, - Windows 7 - contains some hidden(extended) context menu options which are visible if you hold <SHIFT> key when right-clicking on the folder or file and give you quick access to frequently used extended options.
So, the main and most usable are:
1. <SHIFT>+<right-click> on the empty area of the Desktop shows the extended menu option Open Command Window Here:
Desktop:

Folders/ Directories:

Executable file:
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Shortcuts(.lnk) file:
+file.png)
Navigation Pane In Windows Explorer:

Start Menu:
Start > press <CRTL>+<SHIFT> and <right click> on an empty area in Start menu, and you'll get a hidden option Exit Explorer. This option was available in Windows Vista as well.