I made a little app called "Flickbook" for the iPhone and iPod touch that lets you make animations. I wanted to keep it fast and simple, so I kept close to the idea of creating an analogue to when you made little animations on the corners of pages in a textbook. The drawing tools are simple, though we have included some nice touches such as colors that multiply (for easy shading), unlimited undo, and a nice minimal UI.
I hope this is OK to post in the critique forum, though I really value the thoughts of everyone here on CA (it is an art app after all ), and would love to see what you think would make it stronger.
the site with a video showing it in action is at http://flickbookapp.com