You might know the situation that you needed to move a comment (or even more of them) from one post to another. You would have to mess around in your database at a couple of places to accomplish this.
Now I developed this little plugin which will allow you to move comments with some simple clicks. You won't need it often, but when you do, you'll be glad it exists.
If that's what you need, visit the plugin's home page and grab a copy.