Polleverywhere is an online audience response system service. Teachers can create polls and have students respond either immediately using a computer or mobile device, or leave the poll open for a longer period of time for responses. They feature educational pricing and a free option that allows up to 32 responses per poll.
Simple chat room that can be used as a backchannel for classroom or training. Can be used on the web or via a mobile device.
View our discussion: Which of the backchannels do you prefer for teaching/training?