how can i set up mamp or web sharing to show clients php application remotely?
I personally prefer using Web Sharing and installing only MySQL Server, just to stick with the  Mac OS X Apache setup.

Web sharing has support for PHP, all you need to do is remove the comment (#) from the following line of the file /etc/apache2/httpd.conf:

#LoadModule php5_module      libexec/apache2/libphp5.


So it becomes:

LoadModule php5_module      libexec/apache2/libphp5.so


The PHP module includes MySQL support, so you just need to install the MySQL Server, turn it on and then you are ready to go.

After turning Web Sharing on, put your .php files inside your personal Site folder, and access it on your browser using the address informed on the Web Sharing activation screen, inside Settings.