The guys at DigitalOcean have written a great article with the choices you have when designing your webapp insfrastructure needs:
https://www.digitalocean.com/community/articles/5-common-server-setups-for-your-web-application
good read!
Digital Ocean is now offering the possibility to deploy Ruby on Rails with Ubuntu 12.10.
Here is the guide: https://www.digitalocean.com/community/articles/how-to-1-click-install-ruby-on-rails-on-ubuntu-12-10-with-digitalocean
I will be able to give you feedback about the experience once I try it!
Thanks to this article http://www.chimerasaurus.com/2013/01/nginx-requestssecond-raspberry-pi-vs-amazon-ec2/ I have learnt about the existence of Phoronix Test Suite which I would like to try in my servers to find out whether the performance is better with nginx or apache.
And another option to run performance tests is Blitz.io
