You won't be able to use Greasemonkey to surface information that is inaccessible, like who upvoted what, unless I'm missing something?

You could write a Greasemonkey script that would would track what users who have installed it have up-voted. Although that is not very elegant (users need to be convinced to trust it and install it) nor effective (your dataset will be self-selection-biased to that segment of the community), it would be a kind of an interesting solution to play with.

yes, that second paragraph is what i was referring to.

its not the best or ideal solution, but its a solution that would make the concept possible.