[kh99]

OK, I guess you could do something like this, at hook postbit_display_complete:

$forumids=array(1, 2, 3);
$show['threadcount'] = in_array($post['forumid'], $forumids);
if ($show['threadcount'])
{
   $threadcount = $vbulletin->db->query_first("SELECT COUNT(*) AS count
                              FROM ".TABLE_PREFIX."thread 
                                WHERE postuserid = ". $post['userid']." 
                                    AND forumid IN (" . implode(',', $forumids) . ");
   if ($threadcount === FALSE)
      $show['threadcount'] = false;
   else
      $threadcount = $threadcount['count'];
}

and then in the postbit_legacy template, something like:

<if condition="$show['threadcount']">
Threads: $threadcount<br />
</if>

I see you said that you want it to be a link, but I don't know what you want it to link to. But you can probably change the html above to be a link.

I should also point out that adds a query for each postbit displayed. If you're concerned about that, you could add a column to the user table and adjust the count whenever a thread is created or deleted, but of course that takes more work and probably a few more plugins. You could also keep and array for users that you've already done the query for, so if for instance the same user posts 5 times on a page, you'd only be doing it once.