I'm a fan of easy ability to downvote and upvote.
What I would be interested in is a more sophisticated ordering than by net number of votes. For example, I'm sure some people's upvotes correlate well with my own (and probably some people's downvotes correlate with my upvotes!) If comments could somehow be ordered by how likely I am to upvote them, based on historical correlations between my and others' votes, that seems like an interesting approach.