As fun as blogging is, in many ways it's still a one way conversation. What I mean is, unlike a forum where all participants have equal say in posting or responding, the creator of a blog really has total control over what gets shown on the site, by way of moderation.
So anyone who reads a large number of blogs, then makes comments, and then wishes to follow up on those comments - I've found an easy way to do it. www.cocomment.com The site is still in beta, so there are some quirks, but it's been the simplest way to track the conversations I have on other blogs that I follow. They all turn up in one convenient location.