Tracking comments got much easier... Joseph @ Sellsius introduced me to Commentful a couple of months ago, but the user needs to add each comment url they are tracking, a simple task but often forgotten. Then, when there is a comment followup, the user needs to link back to the site itself... I stopped using it...

CoComment  automates the process of recording and displaying comments from all the sites you're tracking in a reader-like appllication... seems to work well so far...

(Thanks to Drew for mentioning CoComment in passing in his MyBlogLog commentary).