My first brush with Cloud Computing was when I leased a virtual server from a service called Hawkhost, as a way to consolidate a few of my web development projects at the time into a single web server. Since then, I have used several cloud services for hosting websites and other web services, including Rackspace, DigitalOcean, and Amazon EC2.
cPanel/WHM is my choice software for web stacks. I currently use WHM to power my cloud web server, which provides services including HTTP, DNS, mail, and FTP for my several web projects. I've also used other linux-based cloud solutions, including OpenStack, which I interacted with over the course of a semester in a UAHuntsville cloud computing course.