Up at the top of the thread (not the top of the page itself), at the center of the thread message is a menu choice called "Thread Tools."
Open up the drop-down menu and select "Subscribe to this Thread."
Then, you can select what sort of notification, if any, you want. If you don't want notification, you can still subscribe to the thread and then you will have a collection of threads that you are interested in always available to view.
To see the list of subscribed threads, you just click on "User CP" right in the middle at the very top of any StangNet pages...it is to the right of the "Over 162,000 Members!!" thing...
Or, you could use my method...
Just visit everyday, see what threads have activity, and then mark all threads read before leaving. When you come back, any new threads will be highlighted (could be issues if you don't let the site place a cookie, but I check it out often enough that even if I delete the cookies I seldom miss any new posts)...