Pivotal - Pivotal Software provides enterprise PaaS-based solutions.
Heroku - Agile deployment platform for Ruby, Node.js, Clojure, Java, Python, and Scala. Setup takes only minutes and deploys are instant through git. Leave tedious server maintenance to Heroku and focus on your code.
tsuru - Tsuru is an extensible and open source Platform as a Service software.
Healthy Servers - Making server monitoring easy
Dokku - Docker powered mini-Heroku in around 100 lines of Bash
Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting