Pandoc is a fantastic tool for converting between various markup formats. We write docs in markdown and use Pandoc to convert to other formats.
From the pandoc site:
If you need to convert files from one
markup format into another, pandoc is
your swiss-army knife. Pandoc can read markdown and
(subsets of) reStructuredText,
textile, HTML, and LaTeX, and it can
write plain text, markdown,
reStructuredText, HTML, LaTeX,
ConTeXt, PDF, RTF, DocBook XML,
OpenDocument XML, ODT, GNU Texinfo,
MediaWiki markup, textile, groff man
pages, Emacs org-mode, EPUB ebooks,
and S5 and Slidy HTML slide shows. PDF
output (via LaTeX) is also supported
with the included markdown2pdf wrapper
script.
Pandoc gets extra points for being open source and written in the hotness that is Haskell ;)
