Navigating and Branching a Forum Topic / Discussion

What do people do when a conversation starts to go off in two different directions??

I'd like to request a feature that allows us to "branch" a discussion, and Forum Topic, and then be able to create more "levels" to a conversation in different threads...

Within this, I also want to suggest getting "visual cues" of where in a discussion you are... I'm thinking of something like a "tree" type navigation, to the left hand side, the way you have folders in the Files and Media section..

I would love to have that as a mental anchor for me to be able to keep track of where I am in a forum or discussion... (possibly even using the analogy of a mailbox, and have "unread" for watched discussions where there's new posts, and the words there become bold with a number in brackets of how many new messages are posted..

What do other people think? Would this be useful for them??