Trusted Logic Voting (TLV)

Here's a short piece of analysis looking at the US election scene and what influence small, difficult to detect % shifting of votes has (vote manipulation where the vote is recorded differently to what was actually cast).

http://www.schneier.com/crypto-gram-0404.html#4

To protect against this you need visibility across the entire election - otherwise such small pertubations can be dismissed as local anomalies - rather than seen as a systematic manipulation and repeating pattern.