I've just written a Java program which is supposed to do exactly that:
epub2html1
An EPUB2 file gets extracted to a standard local HTML file collection. An index.html isn't generated automatically yet, but such feature can be integrated easily. Some file references like embedded fonts (CSS
@font-face) won't get recognized, I guess. Currently, I don't provide a binary executable download package for it, so you could either compile it for yourself, or I could prepare such a package on request.