Aaron Pollock has posted a detailed guide that will help you get a full PHP development environment set up on a VPS, complete with a domain name and self-signed certificate.

I've been developing PHP apps for over eleven years. PHP remains 85% of what I do on a daily basis. Over that time, I've tried lots of WAMP packages to run sites on my Windows computers and, since going Mac, I've used the native Apache install that comes with Mac OS X. Six months ago, I decided to try out a remote VPS for my development. The results have been so good that I forget the pain I used to experience on a daily basis doing it any other way.

He walks you through the entire process (you'll need a VPS first) - it uses an Ubuntu-based setup, but the instructions are relatively easy to port over to other distributions. He helps you set up the system's hostname, install all needed packages/tools and generate the wildcard self-signed SSL certificate. Finally, he shows how to configure Apache's virtual hosts and set up a basic site.