Rhys Wynne

This plugin quite simply lets you know where the users entered your site when they leave a comment. A lot of people who joined the do-follow movement are listed on sites which are a target for comment spammers. To those who suffer comment spam can now find out the page they come from, and block accordingly.
This plugin uses a cookie to track the commenter, so if the user hits the first page first, they will still be tracked.

InComment

Adds an extra "referral" note to the bottom of comment forms, so you could see where people come from comment. Useful for finding resources  …

Julian Widya Perdana

DoFollow State let your WordPress webblog have dofollow structure for all links including links on comments. It also remove the rel=”external nofollow” attribute from default wordpress comments-template and it also gives additional meta tag robots with content “index, follow” for every pages.

DoFollow State

DoFollow State let your Wordpress webblog have dofollow structure for all links including links on comments.

InComment vs DoFollow State