The exceptionally cool follow-on to this is David Chaum's work on using visual cryptography for voting -- http://www.constitution2.org/wiki/files/2004_chaum_

The exceptionally cool follow-on to this is David Chaum's work on using visual cryptography for voting -- http://www.constitution2.org/wiki/files/2004_chaum_secret_ballot_receipts.pdf People have since built further on that work, but I seem to recall that Chaum's paper is what started a wave of work on end-to-end verifiable voting.