I ask because it is an incredibly useful feature than is buried in the UI so it is hard to find for new users.
So do you use it?
(What it does it track your favorite threads and tells you if they have any new posts. They are great if you want to track less active fanbases or threads.)
EDIT: YOU ADD THREADS TO YOUR BOOKMARKS USING THE "ACTIONS" DROPDOWN THAT IS AT THE TOP OF EVERY THREAD.
