Google App Engine - A powerful platform to build web and mobile apps that scale automatically.
browserling - Live interactive cross-browser testing from your browser.
Salesforce Platform - Salesforce Platform is a comprehensive PaaS solution that paves the way for the developers to test, build, and mitigate the issues in the cloud application before the final deployment.
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.
AWS Lambda - Automatic, event-driven compute service
DigitalOcean - Simplifying cloud hosting. Deploy an SSD cloud server in 55 seconds.