Remove WordPress’ NoFollow Without A Plugin - blogpost

example1.php

<?php
function comment_author_link_mine( $comment_ID = 0 ) {
    echo get_comment_author_link_mine( $comment_ID );
}

function get_comment_author_link_mine( $comment_ID = 0 ) {
    /** @todo Only call these functions when they are needed. Include in if... else blocks */
    $url    = get_comment_author_url( $comment_ID );
    $author = get_comment_author( $comment_ID );

    if ( empty( $url ) || 'http://' == $url )
        $return = $author;
    else
        $return = "<a href='$url' class='comment_url'>$author</a>";
    return apply_filters('get_comment_author_link', $return);
}
?>

example2.php

<?php comment_author_link(); ?>

example3.php

<?php comment_author_link_mine(); ?>

example4.php

$return = "<a href='$url' rel='external nofollow' class='url'>$author</a>";

example5.php

$return = "<a href='$url' class='comment_url'>$author</a>";