I added a WordPress plugin called CommentLuv about a month ago, and it’s turning into a wonderful program.
Basically, its purpose is to encourage people to leave comments on your post, and if they put in their blog information it will go into the blogosphere and look for the last post they made, and it will show the link to that post on your blog. This encourages other visitors to look at the link, see what the commenter might have been talking about, and, hopefully, encourages them to visit that blog.
It also gets around some blog versions that automatically have comments set to “nofollow”, which means that a person leaving a comment get no love back to their sites as far as linking is concerned, and since many people leave comments not only to be heard, but hoping for backlinks to their sites, CommentLuv helps them out, and you also, since creating links for your site is part of what it’s all about.
Anyway, you can get the plugin at the link above, and of course you can test it out first by writing a comment on this blog. 🙂