Look at my CoComment tracker tool in the sidebar.
From the 'About' page at CoComment:
What is coComment?
coComment is the only service that allows you to enjoy the full potential of blog comments on the web. Before coComment, the blogosphere was not a global conversation, but tons of fragmented, hard to follow, and untrackable discussions.
Using coComment, you can now keep track of what you have been commenting on, display your comments on your blog, and see what is new in the discussions you are participating in (if other users are also on coComment).
tags: comments blogging blogs blog tool coComment socialsoftware web2.0