This virtual classroom/web meeting application allows you to meet with up to 200 people for free. You can video chat, share your screen, run polls, and present PowerPoint shows.
Google Spreadsheets script that can help you manage the flow of Google Drive files that students share with you. Will create folders for you for as many course sections as you need.
Create an online board with images and text. Participants can add their own ideas and vote on their favorites. Invite participants by email or share a URL.
A Google+ Game for Hangouts. You and others (your Google+ contacts) race with each other to find famous works of art within Google maps (indoor street view). Currently, the Palace of Versailles is the only available game.