Privacy Settings added to Comments?

Is there any mod or thought of a mod that would allow for privacy settings to be set to the comment section of Dolphin also adding tags and or categories to it could add quite a bit of flexibility.  Turning comments into private comments and or allowing for the categorizing and or tagging of them as well could be very helpful and allow for member's to track their own comments...  I searched for a mod but saw nothing available for this...  I can't be the only one who has wanted to or asked about this am I?

Something more than using the membership level Actions settings?

Categorizing and/or tagging comments... too complicated for my sites.  
Not that I'm criticising your ideas... whatever works. 

Yes I've thought about the membership levels but privacy handles it in a better way...The types of conversations that need to go on or can go on are better served with permission levels...Membership levels allow for cross viewing... I am looking sometimes for person to person comments with the ability to add or take away people...to or from the conversation... Permission based viewing is so important and comments is the one common demoninator throughout the site so it really has the ability to tie quite a few modules together... 

Also with timelines and the ability to organize the comments really helps in a CYA moment.  It really would help to tag them at the least but categorizing the would also allow for large numbers of people to organize said comments...