I've found another online whositswhatsits that I'm just in love with. It's called coComment and has been around way too long for me only to be using it just now. It lets you track the comments you leave, so you can see when someone adds a comment after the one you left (perhaps the blog author responding to your comment - I always forget to check back and see if they've done that!).
How handy!!! I love it!
And you don't really have to do anything because it just recognizes that you are leaving a comment and keeps track of it for you. As long as you use Firefox anyway.