I shudder at the ramifications of some of these suggestions. Users do what you pay them to do. For example, paying people to up vote/down vote from New would result in just that -- not in people clicking the links and thoughtfully evaluating the content. And denoting high karma users more visibly would result in more karma boost activities. The end result of that is National Enquirer style headlines.

There is a change that would probably help: allowing a difference in signaling between agree/disagree and signal/noise. The definition of up/down voting is closer to ham/spam than agree/disagree, but people tend to use the arrows for agreement instead. It's hard to behave otherwise, by up voting a well argued comment you think is wrong, for example. It would be easier to highlight quality if multiple axes were available.