Sean Coates has a new post today sharing an example push process for the times when you either just need to push code (without the build process) or you're just deploying something simple - a "deploy on push" hook built into your github repository.

Sometimes, you just need to deploy code when it's ready. You don't need a build; you don't need to run tests - you just need to push code to a server. If you use git and GitHub (and I think you should be using GitHub), you can easily deploy on push. [...] There are really only three things that you need, in most cases, to make this work: a listener script, a deploy key and associated SSH configuration, and a post-receive hook.

He explains what each part of the process does and includes the simple PHP script that github calls to make the deployment (it's specific to his example, but you get the idea). He walks you through setting up the deploy key (a SSH key generated on your server) and how to get SSH to use this key when github comes knocking.