Same as on youtube videos; you can like/dislike. This is self explanatory. And an Edit/delete oneself's own post would be good as well for such times when you double post the same message by accident or when you wish to add more to your post.
What about some group of people (like moderators, only more people with less power) that are manually picked by the moderators that if they like/dislike someones post, they can give/take one AP from the poster. They also have to shortly explain to each poster they liked/disliked their post, so that there would be no problems with the "critics"
And where would these people come from?
Mods already take a post/AP away if they "dislike" a spam comment :P
If you were to have critics of comments, they would have to be... a seperate type of Mod. Not with the powers of being a mod, like colored text and being able to lock or delete threads and posts, awarding merits. They could be like a board of 30-15 people that the Mods trust to make balanced decisions on comments. Yeah. That would be kind of cool. A critic board. nice. Then you could assuure that thoughtful comments on games are awarded. There could be seperate ciritc boards... For each type of game. say we have 40 people that are critics. take 5 of them and assign them to a different section of games and they could all look through the comments faster than the mods together. Then the critics present the mods with the more thoughtful comments including the link, and the Mods decide to give a merit or not. THAT WOULD BE FRIGGIN SNAZZY.