Animated Arithmetic is a project I started a while ago to try to visually show complex arithmetical operations as if they were being done by hand, step by step, using elementary-school algorithms. I originally had very high aspirations for what I was going to build (e.g., matrix multiplication, approximation of pi, RSA encryption, etc.), but at some point dropped it to pursue other things. If somebody had $10,000 lying around to finance further development, I'd be happy to pick it back up again.