At this moment every user account have the option to vote indefinitely (good or poor votes) on many comments or 1 on 1 comment (restriction is now per useraccount)
I made a simpel top 10 module who rangs the good and poor votes.
A couple of our users on our site, make more than 1 account to stay on top, because with many accounts they can vote many time on 1 comment.
Could you make a restriction on IP address?
Greetings Osman from Turkey

(Sorry for my bad English)