ShowMe is an interactive whiteboard screencasting app. ShowMe allows you to record over an interactive whiteboard space while explaining and annotating as you go along. Student accounts can be created by the teacher for easy sharing of their work.
Explore the ShowMe website to see how others have used this app. As with much work published on the web, not all of it are the best examples, but they will provide you with ideas.
Once you watch the screen cast below, please comment on how you might use this with your students.