Google Drive Add-ons just keep getting better and better. If you aren't using any Add-ons provided when using your Google Drive, you are missing some great productivity functions. Here are a few that you might want to check out.
FLUBAROO - The best ever. Never hand grade a test again.
FORMLIMITER - Set specifics like dates and times when people can access your Google Form. Great for setting time/date limits on a test for students.
FORM NOTIFICATIONS - This Add-on lets users create and configure email notifications that are sent when a Form receives submissions.
ADD REMINDERS - Use with Google Sheets. Receive email reminders before dates in a specific column of your Sheet are reached.
G(MATH) - Create graphs (including plotting points) and write complex math directly in a Google Doc.
EASYBIB BIBLIOGRAPHY CREATOR - Easily create a bibliography for research papers. Automatically cite books, journal articles and web sites. Format citations in MLA, APA, and Chicago style.
TABLE OF CONTENTS - Automatically create a table of contents in a Google Doc.
THESAURUS - Get synonyms, antonyms and for your Google Doc.
EASY ACCENTS - Add accents from foreign languages into a Google Doc.
TAG CLOUD GENERATOR - Great for English classes. This Add-on lets you generate a word lists in the side bar of a Google Doc that contains more than 100 words.
TEMPLATE GALLERY - Find lots of professionally designed templates to use as your own. Everything from calendars, schedules, invoices, resumes, letters, and other great templates.
GLIFFY DIAGRAMS - Insert a diagram, flow chart, venn diagram and other professional looking diagrams.
KAIZENA - I use this Add-on in my classes. Speak instead of write comments on student docs. Makes it more personal and you can speak directly to specific parts of a students document.
OPEN CLIP ART - Search through more than 500,000 clip arts that can be inserted in a Google Doc.