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  …

English 
140follow removes NOFOLLOW from author link if the comment has more than XXX characters. 
The character count can be adjusted at the admin pannel. NOFOLLOW also can be added 
to single comments if you add “/dontfollow” to the end of the author link.
Deutsch 
Das Plugin ersetzt rel=”external nofollow” durch rel=”external” aus dem Autor-Link, 
wenn der Kommentar mehr als XXX Zeichen besitzt. Die Anzahl der Zeichen kann 
einfach im Adminbereich beliebig eingestellt werden.
Einzelnen Kommentaren kann das NOFOLLOW-tag wieder hinzugefügt werden, wenn 
einfach “/dontfollow” (Danke an Oliver Bockelmann) zum Link hinzugefügt wird.

140follow

140follow removes NOFOLLOW from author link if the comment has more than XXX characters.

InComment vs 140follow