Perhaps this feature already exists and I am not aware of it...

Ya read a post, reply to it, and click a button so that post link is saved/stored in a folder?

I second that one

I triple. But I am willing to bet the answer will be to look at your own profile and check at your recent posts and check for yourself if someone replied.

However, sometimes I would like to watch a thread without necessarly posting a reply that adds no value.