+1 on the goodness of paper-trails. This was my strongest single objection to the Diebold systems currently in place, the utter lack of a paper-trail. I want it to be like credit-card purchases: after tallying up your ballot (and asking you to double-check it) it asks for a signature with one of those electronic pen thingies[1] and prints out two copies with the signature: one goes to the election judges, the other you take home as your receipt. Simple as that.

[1] I like the idea of requiring a signature much better than requiring ID, although there'd have to be some mechanism to allow people who can't write their name to vote.