These are plugins I personally use and feel really enhance my comments page not only for me but for those who comment as well!
The support is very quick, especially if you contact them via twitter. I love this plugin because it enables the commenter to quickly link to and display their OWN recent blog entry at the bottom of their comment. It brings them more traffic, gives you something new to read (and comment on!)
Basically this allows you to remove that pesky “nofollow” attribute from links. What that does is, again, bring more traffic and page rank to those who comment on your site! You can read more about the “nofollow” at SiteSketch101.
Subscribe to Comments
Just as the title suggests, this lets the commenter “subscribe” to the comments. This is great because I know if I leave a comment on a blog, I like to keep in the loop so to speak, return, etc.
This easily adds a field for people to input their twitter id. I’ve found that my commenters tend to get new followers this way!