Hi,
I am in an early stages of planning to fork Calibre-eBooks Database.
The first part is the redesign of database storage/organization. The way I envision it is that each instance of a book record, from "<author>\<Title>\" will be just some almost random numerical archived zip file <some number>.zip.
Inside the file I will have the ebooks and other data files associated with it.
The second part is the data itself. I am thinking of moving it to almost html style formatting. Like this
<book>
<file>filename</file>
<format>
<format:1>pdf</format:1>
<format:2>djvu</format:2>
</format>
<title>Some Title</title>
<author>
<author:1>first middle last</author:1>
<author:2>first middle last</author:2>
</author>
</book>
So, that it will be easier to append functionality in the future and will be easy to make it backwards and forward compatible just by ignoring unknown parts.
This will also allow for nesting tags and nesting other titles and for future expansion of functionality.