It's nice to get comments - and even nicer to reply to them, but you can't if you don't know they're there! Occasionally someone will comment on an old post that you're not keeping an eye on, so it's helpful to have some way of getting notified of each comment.
One easy way is email. In Blogger's "settings" tab, under "comments", you can put your address in the "comment notification email" box. But if you're like me, your email accounts are already on the verge of being overwhelmed. The added effort of skimming those notifications is unwelcome.
I use RSS feeds. I read blogs - maybe including yours! - in Google Reader, a Web service for subscribing to automatically-updated content. You may not know that RSS feeds can also be used to read comment threads. After posting a comment on someone else's blog post, you can usually find a link that says "subscribe to comments on this post" so you don't have to keep coming back to read people's replies to what you said.
To subscribe to all comments on a Blogger blog using Google Reader, click the "Add a Subscription" box in the upper left and paste in the following URL:http://YourBlog.blogspot.com/feeds/comments/default?orderby=published
...substituting the name of your Blogger blog for "YourBlog". Of course, you could also use this to subscribe to all the comments on someone else's Blogger blog, but seriously, who's got the time?