You know how sometimes you lose the thread of a conversation because you were thinking about something else or left the room for just a second? The same thing can happen with comments you leave on a blog. You read a post and you feel like there's something you'd like to add, or there's a question you have that perhaps the writer or another reader can answer, so you leave a comment. Then you move on to the next blog or whatever and find out later that there was a great discussion that ensued, sparked by your comment.
Before it was almost necessary to keep an encyclopedic list of which comment you made on which blog, but now Blogger has added a feature that will e-mail you if there's a follow-up to a post you've commented on. All you have to do is have a gmail account (which is free), then click on the checkbox at the bottom of the comment page (above, left) and you can stay in the conversational loop. Perfect!