If a picture is worth thousand words, then an animation is worth thousand pictures. If you do not believe me, watch this animation of various methods of sorting. When you get to the page, click on each box to get the sort started. I wish I had seen this, when I was learning about sorting.
This is an inspiring piece of work. I am not talking about the sorting algorithms. But the concept of teaching something through visualization. Still an untapped area for building a tools for learning.