Ask HN: how to track replies to your own comments on different blogs

Hello, I guess a lot of readers are in the same situation: you leave comment on a lot of blogs or websites (including HN), and would like to answer any question tot these comments. How do you keep tracks of replies to your comments? Only a few blogs have an option to receive an e-mail for each reply.

I found sometimes week later that somebody ask a question to me regarding a comment, I would like to be able to answer quickly without visiting 100+ sites manually daily.

Any free webapp that would take care of it?