I know double posting is kind of lame, but this is so short I hope no one minds.

Although this won't makecab everything in a folder, it will add Compress as a context menu option to dll and exe files, and expand as an option to compressed exe, dll, inf, and sys. You can select as many DLL and EXE files as you want and left click and you will see "Compress" as an option. Select it, and every one of your selected files will be compressed.

[Version]
signature="$Windows NT$"

[DefaultInstall]
AddReg = addreg

[addreg]
HKCR,"exefile\Shell\Compress\command",,,"%11%\makecab.exe ""%1"""
HKCR,"dllfile\Shell\Compress\command",,,"%11%\makecab.exe ""%1"""
HKCR,".dl_\Shell\expand\command",,,"%11%\expand.exe -r ""%1"""
HKCR,".in_\Shell\expand\command",,,"%11%\expand.exe -r ""%1"""
HKCR,".ex_\Shell\expand\command",,,"%11%\expand.exe -r ""%1"""
HKCR,".sy_\Shell\expand\command",,,"%11%\expand.exe -r ""%1"""

Thanks, perfect!

For newbies simply save as a .inf file using notepad and then right click this file and choose install.

And make sure you have both makecab.exe and expand.exe installed to %windir%\system32\

.....

this is my way

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\*\shell\expand_Cab_file]

[HKEY_CLASSES_ROOT\*\shell\expand_Cab_file\command]

@="expand -r \"%1\" \"\\\""

[HKEY_CLASSES_ROOT\*\shell\CAB_Max]

[HKEY_CLASSES_ROOT\*\shell\CAB_max\command]

@="makecab /v3 /D CompressionType=LZX /D CompressionMemory=21 \"%1\""

all files can be Compressed

and then all cab files can be expanded

THX

Here's my way:

Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\*\shell]
[HKEY_CLASSES_ROOT\*\shell\Expand]
@="Expand"
"extended"=""
[HKEY_CLASSES_ROOT\*\shell\Expand\command]
@="expand -r \"%1\" %cd%"
[HKEY_CLASSES_ROOT\*\shell\Makecab]
@="Makecab"
"extended"=""
[HKEY_CLASSES_ROOT\*\shell\Makecab\command]
@="makecab \"%1\""

It's essentially the same except I add the "extended"="" so that I would have to press Shift and then right-click in order to see these commands. Otherwise they are hidden. Thus, it eliminates the messy right-click menu.