DOC++ is a documentation generator for C, C++ and Java. It generates TeX and HTML output.
DOC++ is Open Source, which means it's freely available and is distributed in source form.
Like other open source projects, as Linux, DOC++ is being developed by several tens of programmers all over the world, coordinated using the Internet. The role of the Internet is essential for such of projects. From a global point of view, the Internet is nothing but a huge open system.
The Open Source (or "Free Software") idea is the most fascinating concept ever imagined. It was invented by Richard Stallman, a researcher at Massachuttes Institute of Technology, who said that the final scope of computer programs is to be shared, so the programs shouldn't be proprietary but instead should be freely distributable in the source form.
This model have many advantages, and it's based mainly on cooperation. The main idea of the Open Source model is that if everybody cooperates, everybody wins.
One of the advantages can be seen in education. Being freely available, the sources can be used to learn various techniques, algorithms' implementation, and so on. Moreover, it allows students to work on real projects, and the changes can then be contributed to those projects, making the world better for everyone.
DOC++ is fully compatible with the documentation system made by SUN Microsystems, called JavaDoc (which is shipped with Java SDK). That means the sources documented with JavaDoc will work without any change with DOC++.
The informations are extracted directly from the header and source files.
The generated documentation is either HTML (so you can put it somewhere on a web page) or TeX, which is very good for high quality copies (useful for scientific or complex documents, allowing generation of equations, tables, etc.).

In the final I'd like to recommend you to read:
  • Open Sources, Voices from the Open Source Revolution, O'Reilly & Associates, 1999
  • DOC++'s Web Page