There are many free servers out there, many of them cost money, many are free. But often these are all restricted. Why not load up your own stack, on your own personal machine? You can do that easier than ever with ready made binary stacks, that install using simple GUI and Command Line utilities.
Want a Ruby Stack? Windows, Mac, or Linux, try out: http://bitnami.org/stack/rubystack
Want an easy Windows, Apache, MySQL, PHP stack? Try out XAMPP.
In a matter of 5 minutes, you’ll have a fully loaded testing environment to continue and grow your development skills. Enjoy.