Wondering
 

Above the thread, click "Thread Tools" then "Subscribe".
I think it lets you know when someone replies to the thread.

Roger

Yep, like Ray said, you can subscribe to any thread. You can choose to receive email notifications when the thread is updated if you wish to, or you can select "no email notifications" if you just want it listed in your favorites list. You can get to the list of threads you are subscribed to by clicking on "UserCP" on the navigation bar at the top of the forum. You'll also see a different icon next to threads you are subscribed to when you are looking at the list of threads in a forum. ;)

That answers that..