EpubToolbox is for packing, unpacking and validating epubs
A simple tool for managing epub files
A simple tool for managing epub files
The toolbox makes it easier to work with epub files
The toolbox implements industry standard validation, and supplies an image checker for iBookstore compliance.
No terminal scripts or fooling your OS into thinking your epub is a zip file.
Actions can be recorded and replayed.
No charge, and it won't stalk you around the internet either. It's also open source and hackable - if you can Java you can make it your own.