Top Hat Monocle
http://www.tophatmonocle.com/

They make it easier for you to keep your students engaged. Features include the following: No clickers to buy. Students can use their cell phones, laptops, smartphones, or iPods to participate in class; b) Allows multiple choice, numerical, and word answer type questions, with real-time graphing; c) Students can participate anonymously or for grades, based on instructor’s settings; and d) Grades are tracked and tallied through the term, and can be exported to a spreadsheet anytime. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog.