One of the biggest problems on forums as you may know is 'posts boosting'. There are users who LOVE to say 'thanks' when ever they can. How can it hurt? Their post count goes up, they have nothing to loose.
There are also users who really like to express their thanks to post but don't like posting a post that looks like they're post boosting.
Then comes the moderators who have to delete people's thanks yous so a thread can look readable with out the thanks yous thrown around.
Finally comes the posters of these useful posts. They have no idea how many people really likes their posts if only some people say 'thanks'.
What this hack does is fix ALL these problems - except those users who like post boosting. This places a button called 'thanks.' When a user clicks on it, it places his username in a box right under the post saying that so-and-so says 'thanks' for the post. Every-one who clicks is placed in one box.
By giving your users the extra feature, you forum will look allot nice and organized. It is a guaranteed liking by ALL the members of your forum.