KikuText is an additional method for teachers to engage in communication with parents. With the free version, teachers get 60 messages a month and 2 classes for messages to 15 parents. A pro version is just $10 a month and you get unlimited messages, up to 7 classes and 170 parents. With the service, parents would get a text message with a comment about their child which they can respond too. The conversation history with the parent would be saved so it can be viewed and know where the conversation left off. An inbox allows for easy viewing and conversations remain safe and private.
Kikutext has messaging templates that make it easy to update parents about what the students are doing in class and they can be customizable as well. Scheduling of the messages is also available. To make it work, you provide a code to the parents that they text in and the information the parent provides is automatically captured. If the cell phone number of the parent is available, you can text them directly as well. See the SlideShare presentation for more information.
Understoodit is a audience response services that allows users to get simple feedback on whether a lecture/discussion/activity was understood or not. With the creation of an account (Free or Paid...although free is limited) users can provide students with a simple URL to provide to students. Using any device students can respond "understood" or "confused." As students answer, data is provided in real time informing teachers on whether or not re-teaching is necessary. See the video on their front page for more information.
ClassParrot is another option in the growing market for SMS messaging with students and parents. Like Remind 101, this service provides many of the same features. You provide students a code which gets them into the system. You create messages on your computer, therefore keeping the students number private. (NOTE: Upon trying to update this post this site was experiencing an error)
Detext. It's a service that allows the parents to be the "Big Brother is Watching," over their child's cellphone. From a web browser, users can review driving history, restrict certain settings, and set up alerts, when a child is speeding for example. Receive alerts via text or email as they happen.