2006: iClicker.

No, this is not an Apple product. It was invented by two physics professors at the University of Illinois. The clicker is a student response system,  that lets teachers poll and quiz students and get results in real time.

For professors teaching big classes, it is a way to gauge the level of understanding in the audience. The professors asks a question, the students click in with their answers, and the results pop up on the screen as a bar chart.