In learning how to use the slider, I created an Obama face slider. It took some quick math to figure out how to get Obama's face within his own eyes, and move so that they cross each other. I wanted to make the faces within the eyes just get larger, and once they are larger to put new Obama's within the four new eyes - but I wasn't able to figure out how. In a future iteration of this project, I'll attempt to do so.
You can try it, here