Often I think that people are more inclined to downvote someone like Eliezer who has the Karma to spare it
I've noticed a similar (or worse) effect in my own voting patterns. More than once I've neglected to upvote something I thought was good because it had very high karma and was posted by a very-high-karma user. My thought process is something like, "Lukeprog has already gotten more karma for this post than many users have altogether. Does he really need another upvote?"
The largest bias in voting I've noticed in my own thinking is when someone else has voted down a comment, and I see no reason it should be either up or down voted. It is very difficult for me to not upvote it to counteract the, in my opinion undeserving, downvote.
People who go back and downvote every post or comment a Less Wrong user has ever made, please, stop doing that. It's a clever way to pull information cascades in your direction but it is clearly an abuse of the content filtering system. It's also highly dishonorable. If you truly must use such tactics then downvoting a few of your enemy's top level posts is much less evil; your enemy loses the karma and takes the hint without your severely biasing the public perception of Less Wrong's discourse.
(I just lost over 200 karma in a few minutes and that'll probably continue for awhile. This happens to me every few weeks. Edit: I mean it's been happening every few weeks for a few months for a total of only three or four. Between 400 and 700 karma lost total I think? I don't mean to overstate the problem.)