PHP-Documentation is a project mainly written in ..., it's free.
PHP Documentation in Man page format
A collection of man pages for various PHP projects. Currently only has the PHP functions in man page format as a reference, but probably will expand in the future with more sources (such as the Symfony 1.x/2.x API).
Well, nothing too fancy actually. It's the current PHP documentation in Man Page format. The PHP Documentation docbook sources are exported to a man page format, by using the phd command. The Man pages are provided as a convinience, so many users don't have to setup the phd program and execute it themselves. Thus, only 'binary' files are distributed.