Crucial Innovations

Comment Links New Tab will allow you to have your comment author name links open in a new tab or window. In other words, instead of leaving your site completely when clicked, they will open in a new tab.
This will increase the likelihood that visitors will continue browsing your website.
Simple, fast, and effective!
<h4>Some of the features include:</h4>
<ul>
<li>Whitelist your domain</li>
<li>Select a css class, id, or custom value</li>
<li>Enter a css value</li>
<li>Open comment links in a new tab or the same tab</li>
<li>Select keep original, external nofollow, nofollow, or dofollow rel (relationship) link attribute</li>
<li>Use an optional title</li>
<li>Option to Compress/Minify Js (javascript file)</li>
<li>Works with http:// and https:// links</li>
</ul>

Comment Links New Tab

Stop sending visitors away - open comment author links in a new tab or window with: Comment Links New Tab.

rrolfe

The CLM plugin allows wordpress admins to have more control over the links left by users who leave 
comments on their blogs. Admins are provided with the ability to remove all author links from comments 
unless the user has made an admin specified number of comments. You are also provided with the ability 
to override that setting with whitelist and blacklist features. The full list of features provided by 
the CLM plugin is below
Features
<ul>
<li>Enables admins to remove nofollow attribute from comment author links</li>
<li>Allows for optional removal of nofollow attribute from links left in the body of comments</li>
<li>Provides admins with the ability to open comment author and body links in a new browser window.</li>
<li>Provides ability for admins to require a specified number of comments before enabling comment author links</li>
<li>Has built in whitelist and blacklist functions to override general setting of required number of comments</li>
</ul>

Comment Link Manager

CLM enables admins to disable author links, open links in new window, and remove the nofollow tag from links that are left in comments by visitors.

Comment Links New Tab vs Comment Link Manager