Disqus adds extra functionality to your blog comments, including the ability to login with facebook/twitter/openID and Yahoo. It also allows for avatar display on the comments. I always felt these logons were more likely to get people to comment, only wish they had linkedIn installed as well.
The free versions look good enough and the installation was a breeze, just like everything else I’ve experienced with wordpress. No complaints so far, Disqus should be status quo on your blog if you want to take it to the next level. You could also try intense debate, but I like my Disqus experience so far, and they even have a Android app to keep track of the comments on your blog.
To learn more about disqus head on over to the website at www.disqus.com
More info on the WordPress plug in page here.
I’ve tested some comments below if you wish to see it in action.