http://aluigi.org/papers/bms/egga.bms
An user posted a strange EGG file so I checked it and found that it's one of the formats used by the korean archiver ALZip.
This is the wikipedia page of the file format:
http://en.wikipedia.org/wiki/EGG_%28file_format%29
I don't like much this archive format from a technical point of view due to how the chunks of information are handled.
The script support both normal and solid archives, while doesn't support splitted archives, encryption and (currently) the azo compression (it's not the default compression so I don't care).