XR-7, I was discussing this with Georges - why not just have everyone cast their vote right here? I mean, that completely eliminates any sort of cheating, unless someone wants to go pay money for extra votes (please don't). There's really no reason for anonymity once the alt-boosting is gone anyway. Sure, it's a bit more work on your end, but it makes it much fairer (accounts w/out keys can still send PMs, that's why I'm suggesting this instead).
Of course, you'd have to state very clearly how voting is to be done (like "I vote for [name] in poll #[whatever]").