Add a second way to rate users, call it post score (or something similar), the system itself could even work the same way the trust system works (with only minor adjustments).
Might even add options to hide the post scores completely, if you do not care about that sort of governance/moderation.
Considering the number of accounts some people have, I expect this to be abused to silence people. I wouldn't mind a simple + or - to click at each post though (idea taken from Vod, who
owes me a +1), maybe with extra weight for topic starters.
The same could be said for the trust system.
Establish some rules about what ratings influence a post score by what factor,
in the most blunt way, create a DefaultRating account and do the whole DT stuff once again.
(I'm sure people could come up with a better idea how to handle this, just a simplified example.)