Hey,
I think it would be great if there would be a setting which makes this site send you an e-mail when someone quotes your comment on a post which is not necessarily yours.
Yes - very much like the youtube system.
I personally don't want to sit and refresh the site in hope of that someone replies to my comments. (I know we all want a reply sometimes ;P)
Note that I'm not meaning when someone comments on a post which I've created, as that option already exists.