polleverywhere.com

In my high school, the teachers in some classes would pass out "clickers" and they were all synced up  to the same receiver and we had to always get the same one and replace batteries when they're dead.  We would take "Clicker Tests" which were just multiple choice quizzes that the teacher would project onto the board and we would type in the letter corresponding to the answer on our clickers and at the end the teachers would show us how we all did. Instead, I could use the poll everywhere to do the same thing without the hassle of purchasing, passing out, and maintaining the clickers.