Out of the many documentation tools out there, one of the easier is PHPDoctor.

Its dead-simple to get started and i think i may do a quick video but again it is another reason why as a developer you should get firmiliar with the command line, as you can generate web viewable documentation for you entire system or application with a single command.

php phpdoc.php myconfig.ini

Check out the PHPDoctor and be try get a better handle on your documentation, your developers, managements, and business development guys will thank you for it in the future.