Link that counts new/unread posts in forum

This is the code Advanced Forum uses to get the bumber of unread comments in a particular forum. You can expand it to include all forums. This doesn't count nodes, though, so you'd need a seperate query for that and add them.

/**
 * Returns the number of unread posts in a given forum for a given user
 */
function advanced_forum_unread_comments_in_forum($tid, $uid) {
  static $result_cache = NULL;

  if (is_NULL($result_cache)) {
    $result_cache = array();
    $vid = variable_get('forum_nav_vocabulary', '');
    $sql = "SELECT COUNT(c.cid) AS count, tn.tid
            FROM {comments} c
            INNER JOIN {term_node} tn ON c.nid = tn.nid
            INNER JOIN {term_data} td ON td.tid = tn.tid AND td.vid = %d
            LEFT JOIN {history} h ON c.nid = h.nid AND h.uid = %d
            WHERE c.status = 0 AND c.timestamp > %d AND (c.timestamp > h.timestamp OR h.timestamp IS NULL)
            GROUP BY tn.tid";
    $sql = db_rewrite_sql($sql, 'c', 'cid');
    $result = db_query($sql, $vid, $uid, NODE_NEW_LIMIT);
    while ($row = db_fetch_array($result)) {
        $result_cache[$row['tid']] = $row['count'];
    }
  }

  return (isset($result_cache[$tid])) ? $result_cache[$tid] : 0;
}