Few days ago I allowed anonymous people to vote on the forum. The result was discovering a bug about sending email notifications to subscribers of certain posts for every vote as well as receiving a lot more votes than usual, both positive and negative ones.
Now that this bug is discovered, but a solution is not yet found I've reverted back to where we previously were, just registered users can vote. This means less votes and less notifications, but it also means one other thing which is pretty much the biggest purpose of this topic - it appears that many votes might have been of malicious nature. I've seen some entries, like this and this one voted down with negative votes and I'm hard pressed really justifying this. The amount of votes comes down to what diggers would call "burying".
So perhaps anonymous voting wasn't a good idea anyway.
While I'm at it, there is a way to implement digg style voting here with no negative votes and only a "plus" vote. Another option is removing the voting capability in whole, if you believe it not to be sufficiently useful.
So, in any case, opinions are welcome.