Some suggestions
- Use Hook forumhome_complete to avoid file edits
- Use query_read instead of just query to avoid overhead and make the hack compatible with splitted (master/slave) mySQL servers
- Use $db->fetch_array instead of mysql_fetch_array() to make the hack compatible with vBulletins Database Abstraction Layer
- The generated link is missing the Session ID ($vbulletin->session->vars['sessionurl']), so it might not work for non-cookied users
- ++$lnsnbsp; seems to be unnecessary
Furthermore, if you just want 1 record, it's easier to use $db->query_first()
Last but not least: A setting to select the Forum ID (rather than having the User edit the Plugin) would be perfect