Presidium!

Doxygen is a tool for generating documentation from annotated C++ sources, as well as other popular programming languages like C, Objective-C, C#, PHP, Java, Python, IDL (CORBA, Microsoft, and UNO/OpenOffice flavors), Fortran, VHDL, Tcl, and to some extent D.

Read the Docs hosts documentation for the open source community. It supports Sphinx docs written with reStructuredText, and can pull from your Subversion, Bazaar, Git, and Mercurial repositories. The code is open source, and available on github.

LDoc is Lua documentation generator intended to be compatible with LuaDoc and thus follows the pattern set by the various Doc tools:

LuaDoc is a documentation generator tool for Lua source code. It parses the declarations and documentation comments in a set of Lua source files and produces a set of XHTML pages describing the commented declarations and functions.