Gmail in the classroom

Gmail is a quick and efficient way to manage classroom assignments.  It also is a good way to communicate with your classroom community.   I have used Gmail Chat to answer questions and that helps to reduce E-mail overload.  So, I have been using many of the Google tools over my teaching years.  The videos and tutorials are a good refresher and also I am learning new things. I really like the ability to organize contacts and E-mails.
One aspect of Gmail I would like to know more about is Google Voice.  
Overall, I allow my students to use mobile devices for all kinds of uses:  taking instructional videos and sharing them on YouTube, writing notes during class, participating in polls, and taking pictures of whiteboards for review.