Useful Windows variables

Since I did not post much last month, here are some useful Windows variables:

Variable	Type	Description
%ALLUSERSPROFILE%	Local	Returns the location of the All Users Profile.
%APPDATA%	Local	Returns the location where applications store data by default.
%CD%	Local	Returns the current directory string.
%CMDCMDLINE%	Local	Returns the exact command line used to start the current Cmd.exe.
%CMDEXTVERSION%	System	Returns the version number of the current Command Processor Extensions.
%COMPUTERNAME%	System	Returns the name of the computer.
%COMSPEC%	System	Returns the exact path to the command shell executable.
%DATE%	System	Returns the current date. Uses the same format as the date /t command. Generated by Cmd.exe. For more information about the date command, see Date
%ERRORLEVEL%	System	Returns the error code of the most recently used command. A non zero value usually indicates an error.
%HOMEDRIVE%	System	Returns which local workstation drive letter is connected to the user's home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%HOMEPATH%	System	Returns the full path of the user's home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%HOMESHARE%	System	Returns the network path to the user's shared home directory. Set based on the value of the home directory. The user's home directory is specified in Local Users and Groups.
%LOGONSEVER%	Local	Returns the name of the domain controller that validated the current logon session.
%NUMBER_OF_PROCESSORS%	System	Specifies the number of processors installed on the computer.
%OS%	System	Returns the operating system name. Windows 2000 displays the operating system as Windows_NT.
%PATH%	System	Specifies the search path for executable files.
%PATHEXT%	System	Returns a list of the file extensions that the operating system considers to be executable.
%PROCESSOR_ARCHITECTURE%	System	Returns the chip architecture of the processor. Values: x86, IA64.
%PROCESSOR_IDENTIFIER%	System	Returns a description of the processor.
%PROCESSOR_LEVEL%	System	Returns the model number of the processor installed on the computer.
%PROCESSOR_REVISION%	System	Returns the revision number of the processor.
%PROMPT%	Local	Returns the command prompt settings for the current interpreter. Generated by Cmd.exe.
%RANDOM%	System	Returns a random decimal number between 0 and 32767. Generated by Cmd.exe.
%SYSTEMDRIVE%	System	Returns the drive containing the Windows XP root directory (that is, the system root).
%SYSTEMROOT%	System	Returns the location of the Windows XP root directory.
%TEMP% and %TMP%	System and User	Returns the default temporary directories that are used by applications available to users who are currently logged on. Some applications require TEMP and others require TMP.
%TIME%	System	Returns the current time. Uses the same format as the time /t command. Generated by Cmd.exe. For more information about the time command, see Time
%USERDOMAIN%	Local	Returns the name of the domain that contains the user's account.
%USERNAME%	Local	Returns the name of the user who is currently logged on.
%USERPROFILE%	Local	Returns the location of the profile for the current user.
%WINDIR%	System	Returns the location of the operating system directory.

(found in this command shell overview from Microsoft)