One of the features that Movable Type (our blogging software) lacks that is really useful is the ability to notify commenters that someone replied to their post. No one should be required to keep track of all the blog entries they posted comments in.
Now there is a solution. It's called coComment. coComment allows you to subscribe to any blog comment thread with the click of a bookmark in your browser. You can go to a single page on their site to follow all your conversations. Awesome! And it works with our software (though admittedly I haven't tried it).
If anyone gives it a whirl let me know how it works out.