Hi,

I just attended a talk about pdf2htmlEX at the tug 2013 conference ... this looks quite interesting ...

   http://coolwanglu.github.io/pdf2htmlEX/

   http://soft.rubypdf.com/software/pdf2htmlex-windows-version

It works (mostly) ok on even complex context manuals like metafun-s.pdf and fonts-mkiv.pdf.