Touch Drawing created by +François Beaufort stood out.
You can write or draw by simply touching the screen. While the exerimental pressure works sometimes, I find its best to let the app surprise you with text color and line width.
A couple of uses for this app come to mind. The touch centric interface could be a fun way to practice math facts or spelling words. It could also serve as a fun break from a regular drawing program. If you have touch screens in a school environment, this could be a fun app to try.