Stefan M.

This plugin will set all Trackbacks and Pingbacks automatically to DoFollow Links.
The user comments will get after <code>X</code> comments from a unique mailaddress automatically DoFollow status. All other comments have NoFollow, except the Admin enable manually the DoFollow Status. The status which is set manual (if DoFollow or NoFollow) will overrides the automatical process. So, you have the control if someone gets sooner the DoFollow status, or never maybe. Of corse, the automatism can be disabled to do the hole work manually.
You get an support automatism, that you don’t need to check daily, but have the full control power.
Additonal this plugin validated all DoFollow URLs and will notice if there are broken links. Broken Links are very bad the Rank in the Search Engines (SEO).
Home Page of the Plugin: <a href="http://blog.murawski.ch/2010/09/wordpress-manual-dofollow-plugin/" title="IT Blögg - WordPress Manual DoFollow Plugin" rel="nofollow ugc">IT Blögg – WordPress Manual DoFollow Plugin</a>
If you have a wish for new functions, please contact me.

SMu Manual DoFollow

SMu DoFollow has many DoFollow Options (Manual or Automatism) and included URL Validator (Manual, WP-Cron or Cronjob).

Floesub

This plugin enables you to set rules for visitors to get a dofollow backlink on commenting. The rules may be :
<ul>
<li>by characters minimum count</li>
<li>by words minimum count</li>
<li>by comments minimum count</li>
</ul>
The guest can choice its anchor for the author link :
<ul>
<li>by @ separator</li>
<li>by # separator</li>
<li>by % separator</li>
<li>by string you wan’t to separate author and backlink, all is customizable</li>
</ul>
The plugin prevent for SPAM Comment, and advice to write quality content from visitors.
Languages availables :
<ul>
<li>english</li>
<li>french</li>
</ul>
Ce plugin vous permet de définir des règles pour les visiteurs de votre blog WordPress, pour qu’ils aient un backlink dofollow au moment du commentaire. Les règles peuvent être :
<ul>
<li>par le nombre de caractères minimum</li>
<li>par le nombre de mots minimum</li>
<li>par le nombre de commentaires minimum</li>
</ul>
Le visiteur peut choisir l’ancre de son lien :
<ul>
<li>avec le séparateur #</li>
<li>avec le séparateur @</li>
<li>avec le séparateur %</li>
<li>avec le séparateur que vous voulez puisque tout est personnalisante</li>
</ul>
Le plugin protège contre le SPAM de commentaires excessif, et encourage les commentaires de qualités par les visiteurs.
Langues disponibles :
<ul>
<li>anglais</li>
<li>français</li>
</ul>

FloeComment

This plugin enables you to set rules for visitors to get a dofollow backlink on commenting.

SMu Manual DoFollow vs FloeComment