Create online polls/assessments using Qzzr - with analytics. Can embed multimedia and embed your quiz. Visually very appealing and works on all devices. The free version would work well in classrooms.
Naiku's Quick Question allows you to get immediate feedback from your students - simply ask a question, and students respond using any web enabled device, such as a smartphone, tablet, netbook, or laptop.
"Polls, chat tools, and interactive quizzes provide good ways to hear from all of the students in a classroom." Another great list of resources for getting feedback from students by Richard Byrne.