I've just released
YaBBpak Editor 0.1. This open source software can both automatically create YaBBpaks and edit existing ones.
The automatic creation works from two directories (one containing a clean YaBB SE, the other containing a set of modded files). By comparing the two a YaBBpak is produced that you can edit like any other YaBBpak...
Add or remove files from a YaBBpak and rename/move files within it. Features PHP and MOD syntax highlighting PLUS auto completion for MOD syntax.
An installer is provided for Windows users, other OS's can download the source and (unfortunately) have to install Python and wxPython to get it up and running.
Screenshots:
Opening Screen:
Main interface, showing auto complete and syntax highlighting:
LinkDownload
YaBBpak Editor to make modding as easy as it gets