The NY times has an interesting article today of an AP Physics class using wireless hand held devices called clickers to answer questions given to them by their teacher. The response is real time and charted on the screen so the teacher can review if students are learning. The clicker is getting very popular as an educational technology tool and is used in both middle school and colleges as well.
As a matter of fact, Ohio State University has dedicated several pages on its website describing the clicker and practical examples and advice for using clickers in the classroom.
Our school has these clickers and they are often used in large class assemblies when discussion on subjects is required at the meeting.
All in all, it's a great way of getting students involved with their learning.