Some ideas:
For my point of view it is not necessary to have any windows manager, neither blackbox nor enlightenment. The program that is useful for a ebook reader, for example a library browser, reader, pdf or so, this can all be implemented without any libs from a windows manager.
Apart from the X there is also the possibility to make the application purely in framebuffer. Some GUI interface to framebuffer is demonstrated already, especially these two, looks quite interesting:
http://home.comcast.net/~fbui/
http://home.comcast.net/~fbui/fwe.html
The FBUI works only on Kernel 2.6.9. I think it would be very tedious to implement programs based on X.
Anyway Derek, it is really a brilliant idea. Highly respect!