Akeeba Backup
Basically, Akeeba Backup is your safety net. This extension allows you to create fast, safe and easy backups of your website. You can then use the backup to restore your website on any server that supports Joomla through an AXA installer that has been implemented to avoid server timeouts. The configuration of the extension is fairly easy and functions through a wizard that does most of the work itself.
JCE – Joomla Content Editor
JCE is an editor that allows Joomla users without any working knowledge in XML, CSS, XHTML, etc. to edit the content of their websites. It is an environment that closely resembles Microsoft Office, and that is why it is so familiar and easy to use. You can use it to upload, edit and position images, create links that lead wherever you want them to and it also has an integrated spellchecker. It is also upgradable with file manager feature, media manager feature and so on.
Admin Tools
Created by the developer that brought us Akeeba Backup, Admin Tools give us a solution for many of those little problems that can take a lot of time to solve on your own. It updates your Joomla, creates a Secure Administrative ID, provides protection for your website and much more.
AllVideos
AllVideos is an invaluable tool for all websites that incorporate videos and music in their content. By using this extension, you bypass the problem of dealing with large chunks of code when sharing YouTube, Vimeo or SoundCloud and other media elements in your article.