Add a soundtrack to a book or your own writing. You can upload a file of yourself reading the text aloud, or you can choose music and sound effects from the available tracks.
Allows you to click on words and phrases in text and get a translation. Upload the text, or the extension allows you to use text from any website.
Limitations: Free version only allows you to translate 10 phrases per day. The number of single word translations is unlimited.
Create Google Forms using drag-and-drop tools. Allows file uploads (that go to your Google Drive), multi-page forms, and greater control over submissions than normal Google forms.
Upload presentation with notes, and final presentation has text-to-speech of notes accompanying slides.
Limitations: English and German only. The English voice does not sound great.
Create lists of vocabulary and definitions by uploading a document. As of 1/15/2015, this only works for English.
Can export to PDF or Quizlet. As of 1/15/2015, I could not get this to properly export to Quizlet.
Upload videos or link to YouTube. Add video, audio, or text comments at the exact place in the video where you want it. The creator can also add buttons for simpler comments, such as "awesome" or "I don't understand."
Limitations: As of 6/9/2014, the audio and video comments don't seem to work.
Upload a PPT or PDF file, then present it online. The audience can load the presentation on their own devices, including mobile devices. They can respond to questions you ask by clicking on the slide, and then you can show the results. You can also do polls and show the results.