How is the recently viewed done in this forum? Is it with a cookie that stores thread IDs and then uses where forum_id = IN (id1, id2, id3) or is there a table that stores your user name and the threads you have viewed and then does from members as m left join member_to_forum as m2f ON (m.id = m2f.member_id) etc... Or there a completely different way that this forum does it?