Have you ever considered using the TSOA tag for (at least initial) sorting of books? When I used to listen to audiobooks on my old iPod, I'd use the album tag for book title.. and then the album sort order (TSOA) tag to manually control the series name and index of the book within the series. I've wanted this ability in android for quite some time. Ambling comes the closest with its xml implementation, but many of my books are already tagged as I have described above. It'd be nice if I could use Ambling with those tags.

For example, for Terry Goodkind's Sword of Truth novels, my TSOA tags would be as follows:
SoT 01
SoT 02
...
SoT 13

Then, when I browsed by album (or author -> album), I'd see the books listed in order. Make sense?

Thoughts?