I just saw a link to coComment (via an OReilly blog, IIRC - can't seem to find the link at the moment) It looks like a way to track comments that you make on various blogs, providing a way to keep on top of conversations distributed throughout the blogosphere.
I've been doing a low-tech version of this by tagging blog comments on del.icio.us with "blogcomment" so I can periodically check in on them. But this appears to but some intelligence, or at least some automation, behind the concept.
coComment is in a closed beta, by invitation only. If anyone has the goods and feels like hooking me up, I'd love to take it for a test drive. I'm just sayin'...