Adobe Reader has some great features - such as inserting a signature or filling in forms. However, when sharing out completed forms or PDFs with annotations, the notes do not appear. It seems as though this is best used if annotating and then printing.
This is an incredible site to use with mobile devices equipped with a QR Code scanning app. You type up to 100 characters and it generates a QR code that then plays an audio clip. You can designate 1 of 40 languages. While it does not translate, it does speak in the target language. Could be a great resource for foreign language teachers.
This may be the coolest Google trick to date! Doctopus runs a script in Google Drive to automate the creation of docs, hangouts, and more, plus creates a grading platform.