Gmail in the classroom

I have used Gmail as a way to communicate with students;
   - when they are absent.  I can send notes, documents, lesson plans for the day they missed
   - communicate with a class about an upcoming due date or a send them a rubric for a project
   -  flip the classroom a little and send notes and lecture the night before class, so we can complete a lab in class by students starting on it as soon as they walk in