Just been on Conceptart forums for a while and, it's the first forum I've encountered that has such a button (I'm left wondering why that is :blink:): The humble 'Thanks' button for useful posts!
Essentially, it's like a 'quick feedback' button or 'rating' for a comment, as in the 'Like' button on Facebook. Clicks of this button have a track record alike to making posts (so you can tell who's just clicking the thing willing-nilly) and it's helpful for when you want to give some sort of appreciation, if you feel you don't have much to contribute at the time/feel like you're just bumping without new material. Especially so on art threads.
Also, the 'Thanks' you've received on your posts can appear by your name instead of post count (in the case of this forum where post-count isn't shown).
Ex. http://conceptart.org/forums/showthread.php?t=144069 - Same user-panel layout and forum style for the most part. ..Meaning it should be possible on a technical basis xD;
Just throwing it out there :happy: