Zend Server CE is a package containing Apache, PHP, MySQL, and the Zend Debugger. It is a great way to quickly install the full environment needed for PHP development. It is also free.
Installation is pretty simple, mostly download and run.
After installing, you’ll probably want to setup multiple virtual hosts. This requires editing two Zend Server files (conf/httpd.conf and conf/extra/httpd-vhosts.conf) and /private/etc/hosts.
The ZendServer control panel is accessed through the default localhost documentroot folder, so its probably best to leave localhost where it is. Alternatively it may work to copy the ZendServer link that is in /usr/local/zend/apache2/htdocs to whereever localhost gets moved to.
Create new vhosts by uncommenting the vhosts file include in httpd.conf. Then create as many vhost sections as needed. Be careful that any specified log files are within folders with permissions enabled. Also be sure to copy the localhost permissions section in httpd.conf for the location of the vhosts folders (eg. Sites). Remember to setup localhost or the Zend Server control panel will be broken.