For those who don't know what this hack does, here is an explanation.
It will add a Thank You button (like the new reply button) at the top off threads that when clicked for the first time, will make a Thank you post that will add the name of the the user clicking it in the message. Each time it is clicked after the first time, the persons who click it will have their name added to the post.
This is a way to keep threads clean from all of the "Thank you" and "Great Hack" and "I like it" type posts that that can clutter up a thread. Invision Board has a hack like this and it really works great on keeping the threads a little cleaner from "junk posts", as I call them.