SDoP (Simple DocBook Processor) reads a DocBook XML file, processes it into typeset pages, and outputs the result as PostScript (which can easily be converted to a PDF). It is "simple" because it supports only a subset of DocBook, and also because it does not make use of a DTD or stylesheets or any other heavyweight apparatus. It is a single program. SDoP is used to format the Exim reference manual.
dbtroff uses XSLT, Heirloom troff, and Ghostscript to convert DocBook documents to PDF or PostScript. It allows you to flexibly customize the layout of the generated output by using troff instructions, and provides automatic page element positioning to avoid typographical artifacts like “widows”. Full-width and inline pictures can be included, and are also automatically positioned. Currently, only a rather restricted subset of DocBook 4.3 is supported.
The DocBook Authoring and Publishing Suite (DAPS) provides a tool set for easy creation and publication of DocBook sources on Linux. It lets you create HTML (including Webhelp), PDF, EPUB, man pages, and other formats with a single command. It automatically takes care of validating and filtering (profiling) your sources and automatically converts images into a format best suited for the output format. You can easily create profiled source tarballs for translation or review. DAPS supports authors by providing linkchecker, validator, spellchecker, and editor macros. It is well suited to manage large documentation projects with multiple authors using the DAPS docmanager.