We have a new feature a "Thanks" button. It's a nice way to show agreement or appreciation for a good post.
Each time you click the thanks icon (located in each post), you have the opportunity to leave a comment which the post author can read. Comments are not left on the post, but rather in the posters profile.
You can access your own thanks comments in your user cp
(click on user cp on the upper nav bar) and the last 30 or so will be displayed in the center section of the page under "Latest Thanks received" You can also see stats about how many times you've been thanked.
A Pm alert about receiving a thank you is also sent. You can cinfigure notification options for the thanks feature in your profile: here
if you do not want these notifications.