You can help the PHP Team to make PHP better.
Test QA releases (carefully) and report any bugs and incompatibilities in the bug tracking system.

1 Download and install Devserver :    Devserver

2 Download and install a PHP QA Release :

Message from the PHP Team about QA Releases :

THIS IS A DEVELOPMENT PREVIEW - DO NOT USE IT IN PRODUCTION!
For information on new features and other changes, you can read the NEWS file, or the UPGRADING file for a complete list of upgrading notes. Windows sources and binaries can be found on windows.php.net/qa/. You can also read the full list of planned releases on our wiki.