Recently stumbled on Sphinx for generating user docs.

The closest alternative is docbook, so it was pretty much a no-brainer to try out Sphinx considering it lets you write documentation in the uber-friendly wiki-like ReStructuredText format.

It lets you export to HTML as well as HTMLHelp and Latex/PDF. There's also a direct rst2Pdf converter too (although formatting on that one is not as good as Latex)

You should definitely try it out next time you need to write user docs. Two thumbs way up!