PixnTell is a presentation app for both the iPod and iPad. It allows the user to take or choose pictures in their camera roll, draw and caption the pictures, and record their voice in a presentation video.
I see a lot of potential in this app as it is fairly easy to operate, and contains so many functions within it. It could be used in any subject area. Students could explain how to solve math problems, correct sentences, discuss a book, share knowledge about a subject, etc.