Notifications

My apologies if this already exists, but I think it would be nice if I could subscribe and receive notifications when there is updates to different topics/discussions - similar to what happens in some forums.  For example, if I ask a question regarding a plugin, I don't know if someone has answered this question unless I go back and check.  This is time consuming and not practical if I comment or ask questions in several different topics/discussions.  

I'm crossing my fingers that this is already in place and i've just overlooked it until now.  Maybe "bookmark this" plays the role i'm looking for?

Thanks.