Phrocco is the start of a port of the rather nice literate documentation generator Docco to PHP
http://jashkenas.github.com/docco/
Best done via composer global.
composer global require rossriley/phrocco:dev-master
This will install the binary to ~/.composer/vendor/bin/phrocco.
The project is in alpha at this stage but feedback and pull requests are welcome.
Also check out the front end site http://phrocco.info/ for more instructions and example output.