You can have people do this at the start, middle or end of a class. You might collect and use them in another activity. It invites total participation. It could be ‘I have a question’, where you stop the lesson at an appropriate place and have students pose a question they have now, as it relates to the topic. You could either collect them, sort by similarity and address some, or have students do that as a group activity, or shuffle them up and redistribute, asking for volunteers to read them out (of course that way you don’t see them ahead of time.)
TAG cloud.. sounds nice, doesn’t it?