Give your students a homework assignment to answer a question or describe something related to the unit you are working on in class, for example, to describe what they had for dinner. Give them a phone number to call for a Google Voice account and ask them to leave a message there. The voicemail files can then be downloaded as MP3 files and played back in class.
Google Voice is free and has many features, such as voicemail transcription. Have you used it in other ways in your classroom?
Create a website for your class (Heather uses nicenet.org - a free platform that's been around for many years). Use it to host discussions (similar to Facebook posts), post homework, on-line lessons, and email your students all at once.
Do you have a class website? What service do you use to set it up and what have the results been? Do you have any class website best practices to share?