Socrative allows you to deliver easy formative assessment and have students respond beyond multiple choice (Plickers). You will need devices (iPads, laptops, desktops) for your students, but any device will work. Socrative allows you to collect feedback from students through precreated questions, on-the-fly questions and exit tickets. Your students don't need accounts, but rather by teacher "room code" and type in their name. Check out this demo and did I mention it is free!
"Socrative empowers you to engage and assess your students as learning happens. Through the use of real-time questioning, result aggregation, and visualization, you have instant insight into levels of understanding so you can use class time to better collaborate and grow as a community of learners."
