I guess the problem is that when you start to use a service you can't be sure of the quality. There are definitely services out there but they tend to be less than trasparent on the blog directories that you will be submitted to!
http://www.best-web-directories.com/blog-submission-service.htm
http://www.blogsubmissionservice.com/
http://www.links-building.com/blog-directory-submission.php
If you are going to do it I would suggest you locate and submit manually.