If you are looking for an alternative to Wallwisher...say you are using cellphones and none of the touch screens can use it, tryWiffiti; it is so cool. You can design a personalized screen background, embed this into a webpage, and allow your students to post messages to it. They have a great tutorial video to watch:WIFFITI HOW-TO VIDEO. There are a variety of options for sending messages.This site was really developed for businesses to use, but it is easily adapted for the classroom. It would make a great option for a back channel. Check it out; I think you will find numerous uses for this great tool. It really isn't new so if any of you have used Wiffiti, post a comment on how you have used it in your classroom.