Cloudlets are universal server images for the cloud. They're lightweight, version-controlled, and you can export them to any bootable format known to man: Xen, KVM, Amazon EC2, or just a plain bootable CD.
Make continuous deployment safe by comparing before and after webpage screenshots for each release. Depicted shows when any visual, perceptual differences are found. This is the ultimate, automated end-to-end test.
Sample Ansible Playbook for Rack applications that installs Nginx, Passenger, Ruby 1.9.3 + the Falcon Patch, Bundler, and git. It also demonstrates how to deploy a sample Rack application using Ansible.