When you post a comment on a Blogger blog, you can now receive notification of follow-up comments by email! I was really happy to notice this today, as this means you don't have to revisit a blog (or subscribe to per-post comments in a feed reader) in order to know when a reply to your comment is posted.
When you leave a comment on a Blogger powered blog, you will be given the option to have replies sent to the email address associated with your Google/Blogger account, like this:
You'll be sent an email for each response on the post you have subscribed to, and can easily unsubscribe by using the "unsubscribe" link which is sent with each email. Alternatively, when you view the comments page while logged in to your Google account, you will see an "unsubscribe" tick box on the page which you could use instead.
Currently only those who have an active Google account are able to use this service, as replies to your comments are sent to the email address you registered when you created your Google account.
You can read more information about this new service in the Blogger Help pages.