Though this doesn't necessarily count as a blog, we appreciate the presence of Google Reader and it's place in our lives as a blog-facilitator. Before we learned about Google Reader, we would cycle in between many blogs all day long, hoping (ofttimes in vain) for an update. Now, Google Reader keeps track of it all for us!
Basically, Google Reader takes all of the blogs we read and adds a new page to your 'blog book' whenever a blog is updated. It's an easy way to keep track of a lot of blogs, which is a great relief to us, as we spend lots of time keeping track with the blogging world.
Quick vote: This is a great way to keep track of your booming blog population. We'll bark for it!!!