When you want to deploy multiple Rails applications on a single VPS, you might run into problems when they require different Ruby versions. I've got a quick tip for you to easily enable this.
First of all, I'm going to assume you've already got RVM running on your VPS and installed the passenger module on your nginx instance with:
Now, make sure you've installed Phusion Passenger 4.0.0 or higher, since those versions allow for multiple Ruby versions. I'll also assume you've installed multiple Ruby versions with RVM. Let's say ruby 1.9.3-p545 and ruby 2.0.0-p451.
The Example Rails applications is running on ruby-1.9.3-p545 and the AnotherExample Rails application is running on ruby-2.0.0-p451. All that you've got to add to your nginx .conf file (or files) now are the following server blocks: