There have been a number of questions here because people are unhappy with unexplained (and sometimes seemingly inexplicable) downvotes. Some are linked from here...
An idea I haven't seen anywhere is that downvoters should be identified (or at least identifiable) with a list or link near the score, perhaps with some metric indicating how trigger-happy they are with the downvotes.
The idea is that people are less likely to downvote excessively, or out of spite for some grudge, or whatever if they are identifiable - if it damages their own reputation as well as their victims.
I can see reasons against as well as for - one advantage of anonymous downvotes is that it's hard to retaliate against the downvoter, so you can't end up with downvote wars.
I just thought I'd throw the suggestion out there and see what people think.