Try pandoc!

Convert   from DocBook Haddock markup HTML LaTeX Markdown (pandoc) Markdown (strict) Markdown (PHP Markdown Extra) Markdown (GitHub) MediaWiki MultiMarkdown OPML Org Mode reStructuredText Textile Txt2Tags

to AsciiDoc ConTeXt DocBook DokuWiki DZSlides Groff man HTML HTML 5 ICML LaTeX LaTeX Beamer Markdown (pandoc) Markdown (strict) Markdown (PHP Markdown Extra) Markdown (GitHub) MultiMarkdown reStructuredText Textile MediaWiki Org Mode OpenDocument OPML RTF S5 Slideous Slidy Texinfo