You can always create an EPUB. If you enjoy tinkering with HTML, here is a short book on how to create a custom toolchain (disclaimer: I am the author):
Heh, I started using Mutt only because of "peer pressure" during my university years: all cool guys were using it! (Still with Mutt, > 10 years later.)
I think this is somewhat akin to Emacs: startup costs are enormous, but you reap the fruits for the rest of your life.