Just an idea, don't know if it's possible or not? Would be handy if there's a specific user you want to see a thread/post etc. The way I imagine it that user would receive a notification with a link to the thread and post they've been tagged in.
i tend to use the like button on someones post if they have already posted in that thread to draw their attention. a tag option is a good idea though.
I don't have much input nowadays, so I really do put a lot of thought and effort into my rare posts. I hope you appreciated it.