Using REG.EXE, built into Windows XP, Windows Server 2003, and later, or installed on Windows 2000 from the Support Tools folder of of the Windows 2000 CD-ROM, I have scripted AssocList.bat to generate a semi-colon delimited file containing:

Assoc;Ftype;Action;CommandString

Where:

Assoc         is the file extension, like .txt. Two special extensions are Directory and Folder.                              Ftype         is the registry sub-key in the HKCR key that houses the Action definition, like txtfile.                              Action        is the command that appears on the context menu, like Open, Print, and Edit.                              CommandString defines the program and parameter(s) required to perform the Action, like %SystemRoot%\system32\NOTEPAD.EXE %1.
The syntax for using AssocList.bat is:

AssocList \[ComputerName\]

Where ComputerName is optional, defaulting to the local computer.

The output is written to AssocList_<ComputerName>.txt in the current directory.

AssocList.bat contains:

@echo off                              setlocal ENABLEDELAYEDEXPANSION                              set comp=%1                              if "%comp%" EQU "" set comp=%ComputerName%                              set comp=%comp:"=%                              set comp=%comp:\=%                              set file=AssocList_%comp%.txt                              if exist %file% del /q %file%                              set comp=\\%comp%                              set assoc=Directory                              set ftype=Directory                              set ftk="%comp%\HKLM\Software\Classes\Directory\Shell"                              call :quiet1>nul 2>&1                              set assoc=Folder                              set ftype=Folder                              set ftk="%comp%\HKLM\Software\Classes\Folder\Shell"                              call :quiet1>nul 2>&1                              call :quiet>nul 2>&1                              endlocal                              goto :EOF                              :quiet                              for /f "Tokens=4 Delims=\" %%a in ('reg query "%comp%\HKLM\SOFTWARE\Classes"^|find "\."') do (                               set assoc=%%a                               set key=HKLM\SOFTWARE\Classes\%%a                               for /f "Tokens=3*" %%b in ('reg query "%comp%\!key!" /Ve^|find "REG_"') do (                                set ftype=%%c                               )                               set ftk="%comp%\HKLM\Software\Classes\!ftype!\Shell"                               for /f "Tokens=*" %%d in ('reg query !ftk!^|find /i "Shell"') do (                                for /f "Tokens=5* Delims=\" %%x in ('@echo %%d') do (                                 set command=%%y                                 set ftl="%comp%\HKLM\Software\Classes\!ftype!\Shell\%%y\command"                                 for /f "Tokens=3*" %%i in ('reg query !ftl! /Ve^|find "REG_"') do (                                  set prog=%%j                                  @echo !assoc!;!ftype!;!command!;!prog!>>%file%                                 )                                )                               )                              )                              goto :EOF                              :quiet1                              for /f "Tokens=*" %%d in ('reg query %ftk%^|find /i "Shell"') do (                               for /f "Tokens=5* Delims=\" %%x in ('@echo %%d') do (                                 set command=%%y                                 set ftl="%comp%\HKLM\Software\Classes\%ftype%\Shell\%%y\command"                                 for /f "Tokens=3*" %%i in ('reg query !ftl! /Ve^|find "REG_"') do (                                  set prog=%%j                                  @echo %assoc%;%ftype%;!command!;!prog!>>%file%                                 )                               )                              )