I think that it would be useful to see who is voting down good information. It is my theory that voting down is used as a weapon and is not necessarily useful. If we could see who is voting down, we could see if there are any trends. That way, you can continue to allow the freedom of voting down - just giving transparency.
Also, I agree with listing totals - how many up and how many down.
Supporting a Needed Tool for Government Feedback:
A Citizen-Operated Legal System.