Go Soap Box -
http://gosoapbox.com/GoSoapBox is used by educators around the world to break down participation barriers, keep students engaged, and gain insight into student comprehension.
Web-browser based polling, quiz, and discussion service that can be accessed by smart-phone, tablet, computer, or any other web-capable device.
Students can ask questions, contribute opinions, take quizzes, and more.
Instructors create events (such as lectures or recitation) and can attach quizzes, polls, and discussions to the event.
“Confusion Barometer” feature where students have the ability to toggle their status between either ‘I am getting it!’ or ‘I’m confused!’ allowing the instructor to see what percentage of the students are comprehending the lecture.