Of course there are similar applications. You can take a look on the following applications:

• DocBook, and all the tools for it
• The documentation based on comments inside the code (JDoc, PHPDoc)
• Microsoft CHM SDK
• Docbook render on PHP (the announce in the developer's blog)
• convert DocuWiki content for offline usage from LIMB developers.
• ORM Doctrine has it's own documentation parser
• Sphynx — python documentation generator very similar project, but written in PHP and still lacks web interface for viewing docs without compilation of the entire project