Google Docs Addons
Articles Usability
29 Best Add-ons for Google Docs

Google Docs offers only basic features to format a document, and it is bundled with world-class collaboration tools. The application is ideal for co-editing simple documents in groups. But once you need to do something more than just editing, you go back to MS Word and its features. That is where add-ons come in. There are more than three hundred tools that will help you.