Doxygen is a documentation generator for C++, C, Java, Objective-C, Python, IDL (CORBA and Microsoft flavors), Fortran, VHDL, PHP, C#.
DOC++ is a documentation system for C, C++, IDL and Java generating both TeX output for high quality hardcopies and HTML output for sophisticated online browsing of your documentation. The documentation is extracted directly from the C/C++/IDL header/source files or Java class files.
ROBODoc is a documentation tool. It extracts the documentation from your source code and formats it in HTML, RTF, TeX, XML DocBook (PDF), or ASCII. Works with C, C++, Fortran, Perl, Scripts, Assembler, Tcl, Basic, and any language that supports remarks.