Our current minimum setup for one of our apps is as follows: We have an nginx based load balancer that goes between two web servers both running nginx with php

Our current minimum setup for one of our apps is as follows: We have an nginx based load balancer that goes between two web servers both running nginx with php_fpm. The webservers are deployed via svn post commit hooks that call a private network based api to do an export of a tag on svn. Both servers access a single database server running mongodb and there is also a single media server (because most of our projects have uploading capabilities from the admin system and instead of distributing the content on both servers, this single system handles the uploading, storing, deploying to S3 and other nifty things) - this is written in node.js. With this setup we can easily expand by adding additional servers in the server pool, add additional load balancers and round robin dns through those, change the primary database to be a entry point to a cluster of DB's etc. This is our poor man's scaling system - I'm not sure if it's the most efficient, but it has worked for us quite well so far.