Google Doc Add-on's you should be using

What happens when you give Barry Bonds even more steroids? He hits more homeruns. What happens when you install Nitrous-Oxide into a NASCAR? It goes even faster. Google Docs is a powerful beast. But what happens when you add "add-ons" to it? It becomes even more powerful. Even more dynamic. Even more Efficient. If you are using Google Docs and feel comfortable with it, perhaps you need to start using some of the "add-ons" that Google Drive offers. Here's a look at some that I use. 
EasyBib: an easy way to generate citations and bibliographies through Google Drive. Supports Chicago style, APA, and MLA. 
Thesaurus: Sick of always using the same words? Well, activate the Thesaurus and spice up your writing! 
Lucidchart: Quickly create and insert mind maps, flow charts, and other diagrams into your google doc. 
TrackChanges: A great tool for teachers. This add-on allows you to track and approve changes to your documents. 
HighlightingTools: provides you with highlighting tools, grouping tools and selecting tools for review and learning. 
MindMeister: Turn any bullett list into a visually appealing mind map. 
Kaizena: give feedback with your voice and insert it into google docs. Great way to provide feedback for your students. 
Messenger: allows discussion and collaboration while working on a google document. 
ProWritingAid: Check and improve your writing by checking for consistency, plagiarism, acronyms, reduncancies, cliches, grammar mistakes and more.