IDEA - Place a button like the "Thanks" but call it "Contender" or something.
So when people are sifting through the replies and find one that
1. Expands on the original post
2. Provides a great opposing argument
3. Anything that adds value to the thread
You would hit the contender button. After a reply has got XX? number of contender button hits it would be moved up under the OP.
You can set a limit to how many contender spots would be under the OP and that way when someone comes into that thread, they would see the OP and (XX?) best contender replies sitting there at the top.
People can get as much value out of that thread without having to scroll through, and read all the one word/line replies that add no value to the OP.
Just in case people try to abuse this feature, You could have a button that would show up once a reply makes it into the contender spots that would allow people to hit a non contender button, the more the community participates the better the threads will become.
The reason I suggest this idea is because some threads have many pages of replies that offer no value at all.
So by allowing the best to come forward we could save time by reading the most important stuff from the OP, followed by the best replies (voted by the community). If they would like to see any other replys that didnt make it they could go through all the pages afterwords.