hey barthez,
I just started working on a eml2html converter myself, but I would use yours instead for there's no reason to reinvent the wheel. I'm not familiar with ruby, and I don't get the program to run.

So when I run
../eml2html/bin/eml2html test.eml
in my linux terminal I get:

../eml2html/bin/eml2html test.eml /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- eml2html (LoadError)
    from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from ../eml2html/bin/eml2html:3:in `<main>'

Are there any prerequisites I need to be aware of?
Thanks.