I would love to build something like this for encryption algorithms that twiddle bits (DES and friends.) Even for the math-based algorithms, but I have a had time imagining how to make those interesting.
Also, some people have been sharing a video explanation of AES/Rijndael. It is actually rendered from someone's Shockwave Flash movie. https://web.archive.org/web/20051124061027/http://www.cs.bc....