Asus_transformer_firmware_repacker is a project mainly written in Shell, it's free.
Repacks an ASUS Update into a ClockworkMod Recovery compatible update.zip
ASUS Update zip & blob repacker, by supercurio
depends on BlobTools by RaYmAn http://forum.xda-developers.com/showthread.php?t=1068548 https://github.com/AndroidRoot/BlobTools
Repacks an ASUS Update zip into a ClockworkMod Recovery compatible update.zip "SOS" blob is not repacked in order to keep the installed custom recovery