Dropbox is one of the most popular cloud storage services, in part because of its simplicity. The free account comes with 2 GB of storage, and you can use it to automatically sync across Windows, Mac and Linux computers whenever you upload new files to it. There are also apps for iPhone/iPad, Android and Blackberry mobile devices. Installation is drop-dead easy. A folder is created on your desktop and you simply drag and drop files into it.. Then you can access those files from anywhere. You can even share files with other people.