Wat? PHP sends as plain text in Snow Leopard? Reinstall PHP: http://www.entropy.ch/software/macosx/php/
Now apache doesn’t work? Edit /etc/apache2/httpd.conf, uncomment #LoadModule php5_module libexec/apache2/libphp5.so (make it just LoadModule php5_module libexec/apache2/libphp5.so). Now go into System Preferences->Sharing, uncheck then recheck Web Sharing
Now it should work. For some reason, that line being commented out causes a segfault when you request anything besides a directory listing.