I just got PHP and MySQL working on my computer. I am now restarting my web development business and I needed a test server running on my computer. Apache 2 and PHP 5.3 come already installed and compiled on Mac Snow Leopard.
I followed the great tutorial found on www.dwfaq.info. I had to move a couple of files around and update some text in configuration files. I then installed MySQL 64 bit from the MySQL site.
I started MySQL and started the Web server from the sharing area of system preferences.
I then created a webpage with PHP info function: phpinfo()
I saved the file in my sites folder and loaded the page in my browser to see if the PHP server was running.
If you see the above information screen and Apache is running with PHP. If you do not see it, then your server is not working correctly. Go through the tutorial again and try to fix your PHP/MySQL installation.