In his sections, David Weimer does a weekly "exit poll" where students use the same piece of paper throughout the term to record thoughts at the end of section. At the beginning of the semester, students receive a blank sheet that they'll use for their weekly exit poll and then return to David. In the last minute or so of each section, students write down something they thought was interesting, a comment they wish they had said, an idea they were thinking about, and/or a question for David. They are permitted to write whatever they like, regardless of whether it is about the content.
David finds these exit polls useful for several reasons. The exit polls provide a way to recontextualize topics in subsequent classes. For example, David might initiate a discussion by saying, "In the sheets last week, this came up...." The polls also provide feedback on whether the students had the same impression of what happened in section that David did. Lastly, this is an easy way to keep attendance.
David notes that these could be anonymous.