Kbin currently lets you see who upvoted or downvoted a thread/comment through the Activity button.
I think it’s a bad idea to make that information public, as it is almost certainly going to be the cause of arguments, bitterness, drama, and tit-for-tat downvote wars.
Although some might feel that this might be useful for accountability, I think that ultimately, it will cause far more problems than it will solve.
I think it’s perfectly feasible to create a one way hash to represent each user. Easy to generate in one direction (the hash), but impossible to reverse in order to identify the user it was generated from. So in order to ensure that users are not voting multiple times for the same post/thread/comment, all you need to do is check that the hash a user generates doesn’t already exist in the vote record, and if it does, act as a toggle.
But how would you make every instance follow it, cause just one instance not following could break it?