If you click on the digit under the "Replies" column in the Thread view of any Forum, a small Pop Up "Who Posted" window will open. In the window are listed the members that posted with in the Thread along with the post count for each. At the bottom of the window is a link to "Show Thread and Close Window". Clicking this link will close the pop up, and open up the thread.
Handy for a quick look at who posted in a thread, with out having to open up the entire thread. See the attached image: