The first is Chatterbox Pix. It is really simple to use and would be great for lower levels. It's basically a talking picture. You can take a picture, choose one from the internet, or even use one of the images provided (realistic and cartoon-like), then draw a 'mouth' on the image, record what you want to be said, and voilà!
I think it would be great at other levels too if it were used together with, say, iMovie. The idea is to have a celebrity participate somehow - use a picture of your fave celebrity, get them to say what you want to say, and make it part of your video. Cool, n'est-ce pas?
There are also lots of apps for book creation. One, called Book Creator Free is already on the cloud. It seems pretty simple and is used to tell a story. There is no audio feature with this but the finished books are saved in ibooks, which is pretty cool. I can see it being used instead of Keynote, for example, when presenting written work. AP? Higher level grammar classes?